FOR THE PEOPLE FOR EDVCATION FOR SCIENCE LIBRARY OF THE AMERICAN MUSEUM OF NATURAL HISTORY y/^/^ H MEMOIRS AND PROCEEDINGS MANCHESTER LITERARY & PHILOSOPHICAL SOCIETY. (MANCHESTER MEMOIRS.) Volume LV. (1910-11, MANCUKSTKR : -,6, GEORGE STRKKT. 1911. o'■,67^7^(^^ i/ NOTE. The authors of the several papers contained in this volume are themselves accountable for all the statements and reasonings which they have offered. In these par- ticulars the Society must not be considered as in any way responsible. CONTENTS. MEMOIRS. I. On the Origin of Cometary Bodies and Saturn's Rings. By Henry Wilde, D.Sc, D.C.L., F.R.S. Plates I.— III. pp. I— 20 (Issued separately 1 November nth, igio). II. Notes on Scattering during Radio-active Recoil. By Walter Makower, M.A., D.Sc, and Sidney Russ, D.Sc. With 2 7 ext-figs pp. 1—4 {Isstied separately, December i6th, igio). III. The Development of the Atomic Theory : (2) The Various Accounts of the Origin of Dalton's Theory. By Andrew Norman Meldrum, D.Sc. pp. i — 12 (Issued separately, Dece/nber 17th, iqio), IV. The Development of the Atomic Theory : (3) Newton's Theory, and its Influence in the Eighteenth Century. By Andrew Norman Meldrum, D.Sc. ... pp. i — 15 {Isstced separately, December 17th, igio). V. The Development of the Atomic Theory : (4) Dalton's Physical Atomic Theory. By Andrew Norman Meldrum, D.Sc pp. i — 22 (Issued separately, March 7th, igir). VI. The Development of the Atomic Tlieory : (5) Dalton's Chemical Theory. By Andrew Norman Meldrum, D.Sc. ... ... pp. I- 18 (Issued separately, March 7th, igil). VII. The Behaviour of Bodies floating in a Free or a Forced Vortex. By Prof. A. H. Gibson, D.Sc. With Text-Jig. ... ... ... ... ... ... pp. I — 19 (Issued icparately, March 7th, igil). VIII. Studies in the Morphogenesis of certain Pelecypoda : (i) A Preliminary Note on Variation in Unio pictorum, Unio Tiimidtis, and Anodonta cygnea. By Margaret C. . March, B.Sc. Plate mid j Text-Jigs pp. i — 18 (Issued separately, March 14th, igri). VI CONTENTS. « IX. On an Abnormal Spike of Ophioglossum vulgatum. By H. S. IIOLDEN, B.Sc, F.L.S. With 6 Text-figs. pp. i— 13 (Issued separately, March 2ist, i<)ii). X. The Boric Acids. By Alfred Holt, M.A., D.Sc. With 2 Text-figs pp. 1—9 {Isszced separately-, April 20th, igii). XI. Studies in the Morphogenesis of certain Pelecypoda : (2) The Ancestry of Trigonia gibbosa. By Margaret COLLEY March, B.Sc. Plate and 3 Text-figs. ... pp. i — 12 {Issiied separately, A iril 20th, iQii). XII. Some Physical Properties of Rubber. By Prof, Alfred Schwartz and Philip Kemp, M.Sc.Tech. With 11 Text-figs pp. I — 22 (Issued separately, May 2nd, igii). XIII. The Manner of Motion of Water Flowing in a Curved Path. By Prof. A. H. Gibson, D.Sc pp i— S (Issued separately. May 4th, igii). XIV. On the Periodic Times of Saturn's Rings. By Henry Wilde, D.Sc, D.C.L., F.R.S pp. 1—3 (Issued separately. May 8th, igii). XV. Studies in the Morphogenesis of certain Pelecypoda : (3) The Ornament of Trigonia clavellata and some of its Derivatives. By Margaret Colley March, B.Sc. With IS Text-figSk pp. i — 13 (Issued separately. May 30th, igii). XVI. A Plesiosaurian Pectoral Girdle from the Lower Lias. By D. M. S. Watson, JM.Sc. With 2 Text-figs. ... pp. 1—7 (Issued separately. May igtk, igii). XVII. The Upper Liassic Reptilia. Part 3. Microdeidiis Macro- pterus (Seeley) and the Limbs of Alicrocleidiis homalo- spondylus (Owen). By D. M. S. Watson, M.Sc. With 3 Text-figs pp. 1—9 (Issued separately. May 2gth, igii). CONTENTS. Vll XVIII. Notes on some British Mesozoic Crocodiles. By D. M. S. Watson, M.Sc. With 4 Text-figs. pp. i- {Issued separately, May 2<)th, igii). XIX. The Development of the Atomic Theory : (6) The Re- ception accorded to the Theory advocated by Dalton. By Andrew Norman Meldrum, D.Sc... ... pp. i- (Iss7ted separately, May zgtk, iQii). XX. The Conditions that the Stresses in a Heavy Body should be purely Elastic Stresses. By R. F. Gwyther, M. A. {Issued separately. May 22nd, igii). pp. I — 12 XXI. Uioptriemeters. By Prof. W. W. Halbane Gee and A. Adamson. With 8 Text-Jigs pp. {Issued separately, June ist, igii]- -16 XXII. The Development of the Atomic Theory : (7) The Rival Claims of William Higgins and John Dalton. By Andrew Norman Meldrum, D.Sc pp. i- {Issued separately, June 12th, igii). XXIII. On a Specimen of Osteocella Septeiitrionalis (Gray). By Sydney J. HiCKSON, F.R.S. With 3 Text-figs.... pp. {Issticd separately, Jjtne i6th, igii). I — 15 XXIV. An Account of some Remarkable Steel Crystals, along with Some Notes on the Cr}'stalline Structure of Steel. By Ernest F. Lange, M.I.Mech.E., etc. 2 Pis. ... pp. i— 15 {Issued separately, August 2/st, igii). PROCEEDINGS i.— xxviii. General Meetings i., iv., vii., ix., xi., xxiii., xxvii. Annual General Meeting ... ... ... ... ... ... xxv. Report of Council, 191 1, with obituary notices of Prof. Stanislao Cannizzaro, Rev. Robert Harley, Prof. J. H. van't Hoff, and Sir William Huggins, O.M., K.C.B. xxix. — xlii. Treasurer's Accounts... ... ... ... ... ... ... xliii.^ — xlv. List of the Council and Members of the Society ... ... ... xlvi. — Ixi. List of the Awards of the Dalton J\Iedal Ixi. List of the Wilde Lectures Ixii. — Ixiii. List of the Presidents of the Society Ixiv. — Ixv. INDEX. M = Memoirs. P= Proceedings. Abnormal Spike of Opliioglossnm vitlgatum. By H. S. Holden. IM. 9. Action of hydrogen-peroxide on quinone. By E. Knecht. P. xxiv. Adamson, A. and Gee, W. W. H. Dioptriemeters. M. 21. Alpha and ^ rays, scattering of. By E. Rutherford. P. xviii. Alpha particles, large scattering of. By H. Geiger. P. xx. Ancestry of Trioonia gibbosa. By M. C. Marcli. M. 11. Animal metabolism, influence of atmospheric pressure and humidity on. By W. Thomson. P. xxii. Anodonta cygnea, variation in. By M. C. March. M. 8. Atmospheric pressure and luimidity, influence on animal metabolism. By W. Thomson. P. xxii. Atom, structure of. By E. Rutherford P. xviii. Atomic Theory, development of. By A. N. Meldrum. M. 3, 4, 5, 6, 19, 22» Bealey, Dr. Adam, and Dr. Dalton. iiy F. Nicholson. P. xii. Behaviour of bodies floating in a vortex. By A. H. Gibson. M. 7. Bodies floating in a vortex, behaviour of. By A. H. Gibson. M. 7. Boric Acids. By A. Holt. M. 10. Brain, convolutions of. By G. Elliot Smith. P. v. British Mesozoic crocodiles. By D. M. S. Watson. M. 18. Cannizzaro, Stanislao, obituary notice of. By A. N. M. P. xxxii. Cometary bodies, origin of. By H. Wilde. M. i. Convolutions of the brain. By G. Elliot Smith. P. v. Crocodiles, some British Mesozoic. By D. M. S. Watson. M. 18. Crystalline structure of steel. By E. F. Lange. M. 24. Dalton, J. and A. Bealey. By F. Nicholson. P. xii. and W. Higgins, rival claims of. By A. N. Meldrum. M. 22. Dalton's atomic theory, reception of. By A. N. Meldrum. M. 19. Dalton's chemical theory. By A. N. Meldrum. M. 6. Dalton's physical atomic theory. By A. N. Meldrum. M. 5. Dalton's theory, accounts of origin of. By A. N. Meldrum. M. 3. Dawkins, W. Boyd. Origin of Roman numerals i. — x. P. xvi. Development of the Atomic Theory. By A. N. Meldrum. M. 3, 4, 5, 6,. 19, and 22. Dioptriemeters. By W. W. H. Gee and A. Adamson. M. 21. Elastic stresses in a heavy body. By K. F. Gwylher. M. 20. Exhibit of cast of Gibraltar skull. By G. Elliot Smith. P. xviii. Exhibit of Gyi)iiiosporanginin. By F. E. Weiss. P. xxvii. Gee, W. W. H. and Adamson, A. Dioptriemeters. M. 21. Geiger, H. The large scattering of the a particles. P. xx. INDEX. IX Gibraltar skull, exhibit of cast of. By G. Elliot Smith. P. xviii. Gibson, A. H. Behaviour of bodies floating in a free or a forced vortex. M. 7. The manner of motion of water flowing in a curved path. i\I. 13. Gwyther, R. F. The conditions that the stresses in a heavy body should be purely elastic stresses. M. 20. Gymnosporangiiu)i, parasitic on the common Juniper. Exhibited by F. E. Weiss. P. xxvii. Harley, Rev. Robert, obituary notice of. By F. N. P. xxxv. Hickson, S. J. On a specimen of Csteocella septentrionalis (Giay). M. 23. Higgins, W. and J. Dalton, rival claims of. By A. N. Me'drum. M. 22. Hoff, J. H. van't, obituary notice of. By N. S. P. xxxvii. reference to death of. By F. Jones. P. xvii. Holden, H. S. On an abnormal spike of Ophioglossutn vulgaltim. M. 9. Holt, A. The boric acids. M. 10. and Myers, J. E. The hydration of metaphosphoric acid. P. xvii. Huggins, Sir William, obituary notice of. By H. S. P. xxxix. Hybrid of Oxlip {Primula elaiior) and Primrose {P. acaidis). Exhibited by F. E. Weiss. P. xxiv. Hydration of Metaphosphoric acid. By J. E. Myers and A. Holt. P. xvii. Hydrogen peroxide, action of on quinone. By E. Knecht P. xxiv. Influence of atmospheric pressure and humidity on animal metabolism. By W. Thomson. P. xxii. Jones, F. Reference to death of Prof. J. IT. van't Hoft. P. xvii. Kemp, P. Demonstration of effects of heat on pure rubber strip. P. x. and Schwartz, A. Some physical properties of rubber. M. 12. Knecht, E. On the action of hydrogen peroxide on quinone. P. xxiv. Lange, E. F. An account of some remarkable steel crystals, along with some notes on the crystalline structure of steel. M. 24. I>arge scattering of the a particles. By H. Geiger. P. xx. Lower Lias Plesiosauiian pectoral girdle. By D. M. S. Watson. ]\L 16. Makower, W. and Russ, S. Notes on Scattering during Radio-active Recoil. M. 2. Manner of motion of water flowing in a curved path. By A. H. Gibson. M. 13. March, M. C. Studies in the Morphogenesis of certaia Pelecypoda : (i) A preliminary note on variation in Unio pictortmi, Unio iuinidus, and Anodonta cygnea. M. 8. (2) The ancestry of Triooiiia gibbosa. ^L II. (3) The ornament of Trigonia davellata and some of its Derivatives. i\L 15. X INDEX. Meldrum, A. N. The Development of the Atomic Theory : (2) the various accounts of the origin of Dalton's theory. M. 3. (3) Newton's theory, and its influence in the iSth century. M. 4. (4) Dalton's physical atomic theory. M. 5. (5) Dalton's chemical theory. M. 6. (6) The reception accorded to the theory advocated by Dalton. M. 19. (7) The rival claims of W. Higgins and J. Dalton. M. 22. Obituary notice of Stanislao Cannizzaro. P. xxxii. Metaphosphoric acid, hydration of. By J. E. Myers and A. Holt. P. xvii. Microckidus homalospondyhis (Owen), limbs of. By D. M. S. Watson. M. 17. Microckidus macropierus (Seeley). By D. M. S. Watson. M. 17. Morphogenesis of certain Pelecypoda. By M. C. March, (i) M. 8. (2) M. II. (3) M. 15. Myers, J. E. and Holt, A. The hydration of metaphosphoric acid. P. xvii. Newton's theory, and its influence in xviiith cent. By A. N. Meldrum. M. 4- Nicholson, F., Dr. Adam Bealey and Dr. Dalton. P. xii. Obituary notice of Rev. R. Harley. P. xxxv. Obituary Notices. — Cannizzaro, S. P. xxxii. Harley, Rev. R. P. xxxv. Hoff, J. H. van't. P. xxxvii. Huggins, Sir W. P. xxxix. Ophiogkssum znc^gafutii, abnormal spike of. By II. S. Holden. M. 9. Origin of cometary bodies and Saturn's rings. By H. Wilde. M. i. Origin of Roman numerals i. — x. By W. Boyd Dawkins. P. xvi. Ornament of Tngonia clavellata and some of its derivatives. By M. C. March. M. 15. Osteocella sepkntrionalis (Gray). By S. J. Hickson. M. 23. Oxlip and Primrose hybrid. Exhibited by F. E. Weiss. P. xxiv. Pavonazzo marble, exhibit of. By G. P. Varley. P. x. Pelecypoda, morphogenesis of. By M. C. March. M. 8, 11, and 15. Periodic times of Saturn's rings. By II. Wilde. M. 14. Physical properties of rubber. By A. Schwartz and P. Kemp. M. 12. Plesiosaurian pectoral girdle from the Lower Lias. By D. M. S. Watson. M. 16. Prevention of tarnishing of silver-on-glass parabolic mirrors. By T. Thorp. P. iii. Primrose and Oxlip hybrid. Exhibited by F. E. Weiss. P. xxiv, Priimda elatior and P. acaulis, hybrid of. Exhibited by F. E. Weiss. P. xxiv. Quinone, action of hydrogen peroxide on. By E. Knecht. P. xxiv. Radio-active Recoil, scattering during. By W. Makower and S. Russ. M. 2. INDEX. XI Reception of Dalton's atomic theory. By A. N. Meldruni. M. 19. Remarkable steel crystals. By E. F. Lange. M. 24. Roman numerals i. — x., origin of. By W. Boyd Dawkins. P. .xvi. Rubber, physical properties of. By A. Schwartz and P. Kemp. M. 12. Rubl)er strip, effects of heat on. By P. Kemp. P. x. Russ, S. and Makower, W. Notes on Scattering during Radio-active Recoil. M. 2. Rutherford, E. The scattering of the a and p rays and the structure of the atom. P. xviii. Saturn's rings, origin of. By H. Wilde. M. i. Saturn's rings, periodic times of. By H. Wilde. M. 14. Scattering during Radio-active Recoil. By W. Makower and S. Russ. M. 2. Scattering of the « and (3 rays and the structure of the atom. Bv E. Rutherford. P. xviii. Schwartz, A. and Kemp, P. Some physical properties of rubber. M. 12. Sigillai-ia and Sfigmarropsis. By F. E. Weiss. P. x. Silver-on -glass parabolir mirrors, prevention of tarnishing of. By T. Thorp. P. iii. Smith, G. Elliot. Convolutions of the Brain. P. v. Exhibit of cast of Gibraltar skull. P. xviii. Smith, Norman. Obituary notice of J. II. van't Hoff. P. xxxvii. Stansfield, M. Obituary notice of Sir W. Iluggins. P. xxxix. .Steel, crystalline structure of. By E. F. Lnnge. M. 24. Steel crystals, account of some remarkal^le. By E. F. Lange. .M. 24. Sfigiirarinpsis and Sigillayia, By F. E, Weiss. P. x. Stresses in a heavy body. By R. F. Gwyther. M. 20. .Stromeyer, C. E. Process for reproducing sulphide segregations in steel on photographic paper. P. iii. Structure of the atom. By E. Rutherford. P. xviii. Studies in the Morphogenesis of certain Pelecypoda. By M. C. March. (I) M. 8. (2) M. II. (3) M. 15. Sulphide segregations in steel reproduced photographically. By C. E. Stromeyer. P. iii. Thomson, W. On the influence of atmospheric pressure and humidity on animal metabolism. P. xxii. Thorp, T. Prevention of tarnishing of silver-on-glass parabolic mirrors. P. iii. Trigonia clavdlata and some of its derivatives, ornament of. By M. C. March. M. 15. Trigonia gibbosa. ancestry of. By M. C. March. M, 11. Unio pictorum . variation in. By M. C. March. M. 8. Unio titjuidiis, variation in. By M. C. March. M. 8. [ov^r Xii INDEX. Upper Liassic Keptilia. Part 3. By D. M. S. Watson. M. 18. Variation in Uniopictoniw, U. ivmidiis. and Anodojjia Cygnta. By M. C. March. M. 8. Various accounts of the origin of Dalton's theory. By A. N. Meldruni. M. 3- Varley. G. P. Exhibit of specimen of Pavonazzo marble. P. x. Vortex, behaviour of bodies floating in. By A. II. Gibson. M. 7. W.ater flowing in a curved path, manner of motion of. By A. II. Gibson. M. 13. Watson, D. M. S. Notes on some British Mesozoic Crocodiles. M. 18. Plesiosaurian pectoral girdle from the Lower Lias. M. 16. Upper Liassic Replilia. Part 3. Microcleidiis maitoptenis (.Seeley) and the limbs of Microcleidiis homalospoiidylus (Owen). M. 17. Weiss, F. E. Exhibit of fungus Gyinnosporangiufn parasitic on the common Juniper. P. xxvii. Exhibit of hybrid of Oxlip (Primula dalior) and Primrose (/'. acii/is\. v. xxiv. On Sigillaria and Stigiiiariopsis. P. x. Wilde, H. On the origin of cometary bodies and .Saiuins rings. .\L i. On the periodic limes of Saturn's rings. M. 14. Manchester Memoirs, Vol. Iv. (1910), No. \. I. On the Origin of Cometary Bodies and Saturn's Rings. By Henry Wilde, D.Sc, D.C.L., F.R.S. Received and read Ociobcr 4th, igio. As the first Halley Lecture which 1 delivered before the University of Oxford in May last* contained some matters new to astronomical science, it has appeared to me that an abridgment of the lecture, with some additions which have since presented themselves to me, would be of value in continuation of my papers recently published by the Society.f While the principle of dualism is abundantly manifest in every department of knowledge and fully recognized in the attractions and repulsions in molecular physics, the phenomena of the repulsive energy of celestial bodies have so far been unduly obscured by the more general principles of moving force and the attraction of gravitation. The doctrine that the solar system, as at present constituted, was formed by the successive condensations of a nebular substance rotating about a central position, has been more firmly established during recent years through the great advances made in stellar photography, by which many of the nebula; are visualized in various stages of evolution as right- and left-handed spirals, and clearly indicating the direction of their revolutions.;!: * Clarendon Press. Frowclc. 19 1 o. t Manchester Memoirs, vols. 53, 54, 1909, 1910. Phil. Mag. (6), vols. 18, 19, 1909, 1910. X "Celestial Photographs," by Isaac Roberts, F.R.S. Vols, i, 2, 1893. 1899. November iit/i, igio. 2 Wilde, Origin of Conietary Bodies and Saturn's Rings. The more interesting of these nebulse are, M.31 Andromedse, M.51 Canum, M.ioo Comae, M 74 Piscium, and many others from which the origin of planetary systems may be inferred with the same degree of pro- bability as in the historical sequences observable in chemistry, geology, biology, or in any other department of the natural sciences. That the subsequent condensations of planetary nebulae into spherical bodies would be attended by the evolution of an amount of heat sufficient to make them vividly incandescent, is an obvious conclusion drawn directly from experimental science. It will be further evident that, after the heat of compression had attained its maximum, the self-luminous planets would ultimately become dark bodies through the radiation of their heat into free space. It is very generally admitted that the sun, notwith- standing his vast dimensions, would, by continuous loss of heat, ultimately become a dark body like each member of the planetary system. It is also known that the internal parts of the sun are in a gaseous condition and under immense pressure. Some idea of the repulsive force exercised by this pressure may be formed from the ejection of enormous masses of incandescent gas from the surface of the sun to the height of 200,000 miles, with an estimated velocity of 166 miles per second.* Assuming the secular cooling of the sun to be continu- ous, the liquefaction and final solidification of his outward parts would follow in natural sequence in accordance with common experience of cooling bodies, while the central parts would remain in their primitive gaseous condition. From strict analogy, it may justly be inferred that all the planetary bodies have gone through the same stages of * Young, American Journal of Science, 1 871, p. 468. Manchester Memoirs, Vol. Iv. (1910), No. |. 3 cooling as those outlined in the instance of the central body. The notion that the earth and, inferentially, the other planets are solid bodies throughout, finds no support from a reasonable consideration of the constituents of the earth's crust, so far as they are accessible to observation. The late distinguished Professor of Geology in Oxford University (Sir Joseph Prestwich), in his classical work on Chemical, Physical, and Stratigraphical Geology, has clearly demonstrated from the uplift of continental areas and mountain chains, the welling out of basaltic lavas over many thousand square miles of surface and of great thickness, that a comparatively thin crust enveloping a fluid interior is a necessary condition to satisfy the requirements of geologists and physicists. More signifi- cant still is the succession of foldings of the earth's crust and stratigraphic contortions of small curvature, both of which features indicate a thickness of solid crust less than twenty-five miles. How far the imprisoned gases at the centre of the earth and the aqueous vapours near the surface may have contributed respectively to produce these geological changes, it is unnecessary now to discuss, but in the instance of the moon, which has neither water nor an atmosphere, the evidence of intense volcanic action manifested on its surface can only be accounted for by the ejective force of the gaseous substances in its interior, similar to that by which the incandescent gases from the surface of the sun are projected. The fine series of photographic enlargements of the moon executed by MM. Loev/y and Puiseux, of the Paris Observatory, show the greater part of its surface, from the equator to the poles, covered with extinct volcanoes in every stage of formation, similar to those on the terrestrial elobe. Some of these volcanoes are twelve 4 Wilde, Origin of Cometary Bodies and Saturn's Rings. thousand feet in height, with their craters upwards of forty miles in diameter, and are striking evidence of the immense repulsive force which produced them. It has for a long time been considered on good evidence that the planetoids between the orbits of Mars and Jupiter (now numbering more than 600) are the fragments of a large planet which had formerly revolved in an orbit about the same distance from the sun as Ceres, and had been shattered by some internal convulsion. This hypothesis was put forward by Olbers the discoverer of Pallas in 1802, and was made the subject of a memoir by Lagrange in which he determined the explosive force necessary to detach a fragment of a planet that would cause it to describe the orbit of a comet. The nebulosities of the dense atmospheres of some of these planetoids concealing their disks indicate an incipient change of planetary into cometary bodies. Attempts have been made during recent years to discredit the explanation offered by Olbers of the origin of the planetoids, by assuming that the annulus or convolute of nebular substance failed to resolve itself into a sphere, but was broken up into a number of small bodies. There is no inherent improbability in the idea of a nebular convolution resolving itself into a number of discrete spherical bodies as many of such are to be seen in the convolutions of spiral nebulae, of which M.ioo Com;c and M.74 Piscium are the most striking examples. The convolutions of these nebulae contain nebular stars which are involved symmetrically and follow the curvature of the convolutions. M.ioo Comae is further interesting from the fact of its showing elongated fissions of the convolutions previous to their development into spherical bodies. Such discrete bodies, revolving in a circular orbit of the same diameter would, by their mutual Manchester Memoirs y Vol. Iv. (19 lo), No. 1. 5 attractions, ultimately coalesce to form a single planet, as postulated in my paper in connexion with the contraction of the radius vector of Neptune.* As the orbits of all the planets are nearly in the plane of the ecliptic, and also of comparatively small eccentricity, it would become necessary to further assume that all the rings of discrete bodies should revolve in the same plane of the ecliptic, and in orbits nearly circular as do the other planetary bodies ; but Olbers found that Pallas had the large orbital inclination of 34°7, and many others are inclined from 26 to 15 degrees. The eccentricities of some of the planetoids are also very large, that of yEthra being 0380, Juno 0'257, and Pallas 0"238. The periodic times vary between 7"86 years (Hilda) and 175 years (Eros) with the correlated large differences in their mean distances from the sun; Hilda being 3'95 astronomical units, and Eros only v\6 units which thereby intersects the orbit of Mars, 1*52 units. The large differences observable in the elements of the planetoids, clearly indicate them as fragments of a large planet, in accordance with the conclusions arrived at by Olbers in 1802. The illustrious astronomer further assumed that the orbits of all the fragments would inter- sect each other at the point where the explosion occurred. Subsequent observations have, however, shown (which I shall confirm further on) that this supposition, while applicable in many instances, does not hold good as a generalization. It will now be evident, without further discussion, that had the exploded major planet been a solid body throughout as hard as steel, it would still be revolving in * Afanchester Memoirs, vol. 54, 1910. Phil. Mag., (6) vol. 19, 1910, p. 604. 6 Wilde, Origin of Couietary Bodies and Satuni's Rings. its orbit, and would thus have deprived the world of an interesting chapter of astronomical science. A review of the history of cometary astronomy brings out the remarkable fact that, while much has been written on the nature and motions of comets, few, if any, serious attempts have been made to account for their origin. The general opinion of modern astronomers, in accordance with the views of Kant* and Laplace,f is that these bodies are strangers to the solar system, which have been captured in the course of their lawless wanderings from the depths of the stellar universe The principal objection to this supposition is the immense distance of the solar system from the fixed stars. The best determination of the distance of the nearest of them was made by Dr. Gill at the Cape of Good Hope in 1881, which showed that a Centauri had a parallax of 075", indicating a distance of about 25 billion miles, or 9,000 million miles more distant from Neptune than that planet is from the sun. As the attraction of gravitation at the orbit of Neptune is only one forty- second millionth of that at the solar surface, the attractive force at the distance of the fixed stars may be considered a negligible quantity in determining the motions of cometary bodies having their origin in other planetary systems. Granting for the moment that comets actually belong to other stellar systems, the problem of their origin and formation would still present itself for solution to earnest inquirers into the nature and causes of things. The discoveries in cometary astronomy, more espe- cially those of Schiaparelli, that the orbits of certain comets are identical with those of well-known streams of ■ Kant's " Natural History and Theory of the Heavens," Chap'er 3. t Laplace's " Systeme du Monde," 1824. Manchester Memoirs, Vol, Iv. (1910), No. \. 7 meteors, as instanced in the comets of Tempel and of Biela in relation to the November meteors, clearly point to the conclusion that the place of origin of these erratic bodies is within the confines of the solar system, and that they have, consequently, always been members of it. Moreover, all meteoric bodies, as is well known, are mechanical mixtures of elementary substances or their compounds, and further indicate them as the ejectamenta of planetary bodies. That comets are planetary ejectamenta, principally from the larger planets, may be justly inferred from the prodigious force manifested by the ejections from other celestial bodies to which attention has already been directed. The determining cause of the ejection of a comet from any planet would be found in the conjunctive attractions of one or more of their number acting upon that part of the surface from which the cometary matter was ejected. The orbital direction of a comet would be determined solely by the position of the breach in the crust in relation to the orbital motion at the moment of discharge. The motion would be direct when its discharge coincided with the orbital motion of the planet, and retrograde when it was in the opposite direction, as shown in the annexed plate. And, according as the discharge was more or less at right angles to the plane of the planetary orbit, so would the angular direction of the comet in relation to the ecliptic be determined. The discharge of cometary bodies from vents in high planetary latitudes would necessarily have the greatest inclination to the ecliptic. It may be observed in this connexion that some of the large craters on the moon's surface, and of the terrestrial active volcanoes, Hecla and Mount Erebus, are also in high latitudes. 8 Wilde, Origin of Covietmy Bodies and Saturn's Rii/gs. To those who are not familiar with the problems of experimental mechanics, it may be of some advantage to demonstrate more fully the direct and retrograde motions of cometary bodies by further illustrations than those shown in my Halley lecture. It is common knowledge, based on well-established observations, that the axial and orbital rotations of all the planets are in the same direction, the sun also revolving on its axis in the same direction as the planets. As a consequence of the common direction of the axial rotations, the adjoining circumferential parts revolve in opposite directions to each other, as will be seen in the annexed diagram of the Sun and Jupiter. Hence, while the circumferential parts of the planets next to the sun revolve from west to east, the sun apparently revolves from east to west, as is manifest from the motion of the dark spots across the solar disk. That the circumferences of moving circles rotate about their centres in contrary directions at opposite extremities of their diameters is an axiomatic truth which finds its concrete expression in the diagram referred to. This geometrical relation is also practically illustrated in the reaction steam engine of Hero of Alexandria, in which a hollow globe is made to revolve by two jets of steam issuing in contrary directions from opposite extremities of its diameter. Other instances of direct and retrograde motion may also be seen in the Catharine wheels of ordinary firework displays, and in hydraulic turbines with multiple jets around their circumferences. Halley's original conception of concentric spheres rotating within the earth, with a differential motion, is fruitful in leading to the further idea that the ejection of comets from a planet may be periodic from causes within Mane lie ster Memoirs, Vol. Iv. (1910), No. \. 9 itself, in like manner to the eleven years maximum sun-spot ejections of elementary gaseous substances. For it is only necessary to assume that, after the ejection of cometary matter through the double thickness of two concentric shells, the differential motion would retard, or wholly prevent, the further discharge until the vents were again coincident. The planet Jupiter, from his vast dimensions, is the most interesting member of the solar system for the study of planetary and cometary evolution. The great red spot on his surface is generally considered to be caused by luminous vapours at great depths within the globe, if not by the actual incandescent crust of that part of the planet. The great extent and permanency of this spot indicate it as the locus of one of the vents through which comets and cometary satellites have been ejected at different periods of the history of the planet. It is now generally recognized that certain groups of periodic comets are associated in some way unknown with the larger planets respectively ; the comets of short period belonging to Jupiter, as nearest to the sun, and the long period comets (of which Halley's is the most notable member) to Neptune and intermediate planets. All the motions of periodic comets are well explained on the assumption of their moving in elliptical orbits more or less elongated, but the vast tabulated periodic times of comets supposed to move in parabolic and hyperbolic curves are necessarily ultra-speculative. As the attraction of solar gravitation extends far beyond the orbit of Neptune, the motion of a body on the line of an open curve would ultimately be arrested and a comet would necessarily return over the same track, approximately, with a retrograde motion as an unknown lO Wilde, Origin of Cometary Bodies and Saturn's Rings. member of the solar system. Halley's comet, however, is considered to move in an elh'ptical orbit and has, there- fore, the longest periodic time of which astronomers have certain knowledge. As the principle of conservation holds good alike for celestial and terrestrial bodies, the moving force of comets will not exceed the attraction of gravitation beyond the limits of the solar system, and will be much less through the conversion of molar into molecular motion by friction of the discrete particles of cometary matter among them- selves during the act of ejection, as also from the resistance of the medium through which they move in their orbits, and especially near the sun. The principle of conservation, as will be obvious, will hold equally for the comets ejected from the planets of other stellar systems. Hence the absurdity of bringing cometary bodies into the solar system which contains within itself the power of evolving its own comets. Moreover, it will be further evident that this immigration notion might be extended to include the Earth and other planets as bodies from other stellar systems, captured by the Sun in their wanderings from outer space. Jupiter, with his system of satellites, is generally regarded as a miniature solar system formed by the successive condensations of a nebular substance surround- ing the planet. The laws of attraction, moving force, and Kepler's laws have the same relations among his satellites as in the planetary system. The binary progression of the periodic times of the three adjoining major satellites, lo, Europa, and Ganymede (which are very nearly in the ratio of I, 2, 4) indicates an orderly process of evolution similar to that of the binary progression of the planetary distances. Manchester Memoirs, Vol. Iv. (1910), No. I. 11 The erratic movements and irregular orbits of the three outer Jovian satellites recently discovered have, however, presented a new problem for solution in con- nexion with the nebular theory of the evolution of satellites, as it was found that the orbital motion of the outermost one was in a retrograde direction. An attempt has been made to explain the anomaly by assuming that Jupiter at an earlier period of his history performed a semi-revolution about his polar axis, and that all the inner satellites turned over, in like manner, in opposition to the orbital direction of their erratic outer member. An insuperable objection to this ingenious hypothesis is the absence of any causal connexion between the assumed inversions of the axial motions of planets, together with their satellites, and their orbital revolutions, and, consequently, leaves untouched the problem of the retrograde orbital motion of a satellite, which it is the precise object of the hypothesis to explain. The fallacy involved in the scheme will at once be apparent when applied to the orbital rotationsof all the planets which are clearly independent of the positions of their axes of rotation in relation to the plane of the ecliptic. And here it may be useful to apply Newton's ' First rule of reasoning in philosophy,' as laid down in the " Principia " that, ' we are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances ; for Nature does nothing in vain, and more is in vain when less will serve, for Nature is pleased with simplicity, and affects not the pomp of superfluous causes.' I have already said that when a comet is ejected from a planet opposite to the orbital motion its direction would 12 Wilde, Origin of Covietarv Bodies and Saturn's Rings. be retrograde to that of the planet from which it was ejected. The orbital velocity of Jupiter being eight miles per second, a body ejected from its interior at a much greater velocity (which I will call the critical velocity) would, by the diminished attraction of the planet, conjointly with the action of solar gravity, revolve with a retrograde motion in an irregular and much enlarged orbit in accordance with the observations {Plate i). And if ejected with a velocity much greater than that necessary to retain it within the sphere of the planet's attraction, the body would move in a separate and elliptical orbit as a comet. Considering the comparative minuteness of Jupiter's three outer satellites, which are estimated to be less than thirty miles in diameter, and that the orbits of J VI and J VI I are both inclined at 30" to the plane of the ecliptic, and have nearly the same periodic times and distances, these small bodies are hardly entitled to rank as satellites, but may rightly be regarded as planetary ejectamenta. Nevertheless, the discovery of them is of great importance, as furnishing another indirect proof of the planetary origin of comets. Applying the foregoing principles of direct and retro- grade motion of cometary bodies to the explosion of a whole planet between Mars and Jupiter, the fragments projected opposite to the orbital motion would be retarded, and by the action of solar gravity revolve in a smaller orbit than that of the planet before the explosion. On the other hand, the motion of the fragments coincident with the orbital direction would be increased, and by the diminished action of the sun's attraction, revolve in a larger orbit in accordance with the observations. In neither of these cases, however, would the orbits of the Manchester Memoirs, Vol. Iv. (1910), No. 1. 13 fragmentary bodies again intersect each other at the point of the planet's orbit where the explosion occurred. All the observations which I have made on the evolution of the Jovian satellites and cometary ejecta, are applicable alike to the Saturnian and other systems of planetary satellites. The evidence of orderly progression in the periodic times of the inner satellites of Saturn differs in one respect from that indicated by the satellites of Jupiter in similar positions, as the times of revolution of the first and third satellites are in the ratio of i and 2, and the times of the second and fourth are also in the same ratio, as was first pointed out by Sir John Herschel.* Notwithstanding that the actual surface of Jupiter is covered with dense vapours of great depth, just as the terrestrial globe at one period of its history was enveloped with an atmosphere of aqueous vapour which has since condensed to form the oceans, several facts, in addition to those advanced indicate that the Jovian planet has a solid crust of considerable thickness. The remarkably bright round spots which suddenly appear on the planet at irregular intervals, and have been described by Lassell, and also by Dawes, as having some resemblance to lunar craters,j- indicate considerable vol- canic activity below the atmospheric envelope. The eruptive matter from the Jovian craters also produces the appearance of belts on his outer surface as well as those seen on Saturn and Uranus. That these belts and bands are caused by volcanic dust ejected to great heights from the interior parts of planetary bodies is highly probable from observations made on the great eruption of Krakatoa in 1883.+ * " Outlines of Astronomy," p. 368, 1864. t Monthly Notices Roy. Ast. Soc, vol. 10, 1850; Ibid., vol. 18, 1857. X " The Eruption of Krakatoa and Subsequent Phenomena." Report of the Krakatoa Committee of the Royal Society, 1888. 14 Wilde, Origin of Cometary Bodies and Saturn s Rings. The ejecta from this volcano reached a height of more than 30 miles, forming a belt 20° wide on each side of the equator, and made two successive revolutions round the globe in the course of twenty-five days. The optical phenomena attending the eruption also included blue, green, and copper-coloured suns similar to the transient colours observed on the belts of Jupiter. The problem of the origin of Saturn's rings has for a long time engaged the attention of natural philosophers, but no solution has yet been offered of sufficient im- portance to gain the general assent of astronomers. The first of these attempts was made in 1755 by Kant in his " Natural History and Theory of the Heavens," wherein he assumes that Saturn at an early period of its history had the characteristics of a comet and moved in an orbit of great eccentricity. That its tails gradually contracted upon the planet to form a cometic atmosphere of vapours which subsequently changed into the form of a ring entirely separated from the body of the planet. In the " Systeme du Monde " of Laplace the rings are supposed to be the original nebular substance uncon- densed into the form of satellites. This opinion has since been strongly held by astronomers and other scientific investigators and utilised as an illustration of the nebular theory of the origin of planetary systems. Recent spectroscopic and mathematical investigations have, however, shown that the rings consist of a vast number of minute bodies, in confirmation of the views previously advanced by J. D. and J. Cassini in the Memoirs of the F rend I Academy of Sciences in 1705 and 1715. In neither of the explanations of the origin of Saturn's rings by Kant and Laplace is there any suggestion of the Manchester Memoirs, Vol. Iv. (1910), No. I. 15 interior of the planet as being the birthplace of these singular appendages. It is therefore with some amount of diffidence that 1 venture to affirm that they are the ejectamenta of Saturn when its diminishing energies were insufficient to eject a cometary satellite, or a comet with its train of meteorites beyond the sphere of its gravita- tional attraction. And here it may be well to remark that all meteoric and other small discrete bodies are not formed directly from the universal nebular substance, but are necessarily fragments of the solid or liquid parts of a globe, which had a long previous history, involving the evolution of the several series of elementary substances of which the globular body was composed. The dimensions of Saturn's rings are drawn up in the following table for a new determination of the times of their revolutions, and are based upon the commonly accepted equatorial diameter of the planet = 73.860 miles or the semi-diameter of 36,930 miles. The dimensions have been calculated from scaled measurements which I have made of reproductions of the fine photographs of Saturn taken at the Lick* and other Observatories during recent years, and which surpass in accuracy those calculated from observations and micro- metric measurements. The radial dimensions of the rings on the line of the equatorial diameter of the planet have the same propor- tional relations at different angles about this diameter, and constitute the basis of the method of measurements which I have adopted. In accordance with the notation of O. Struve, now generally adopted, I have designated the rings A, B, and C, in the order of their distances from the planet. * Todd, "Stars and Telescopes," 1900. 1 6 Wilde, Origin of Conic tary Bodies and Satunis Rings. ELEMENTS OF SATURN'S RINGS. Distance from centre of Saturn. Time of Revolution. Rings. Sat. Units. Miles. h. m. Exterior A. 2-30 84,937 12 48 Breadth 026 9,602 „ Mid-breadth ... 2-17 80,138 II 45 Interior A. 2-04 75,337 10 42 Interval 007 2,585 ,. Exterior B. ... 1-97 72,752 10 9 Breadth 0-47 17,357 ,, ,, Mid-breadth ... 1735 64,073 8 24 Interior B. 1-50 55,395 6 44 Exterior C. 1-50 55,395 6 44 Breadth 023 8,493 ,, ,1 Mid-breadth ... 1-385 51,148 6 00 Interior C. 1-27 46,901 5 15 liall Space 027 9,971 ,. „ Sat. Ball TOO 36,930 10 13 Mimas 336 1 24,084 22 37 Manchester Mejnoirs, Vol. h. (1910), No. \. 17 The velocity with which a body is ejected from the interior of a planet, as I have said, determines whether it shall be designated a comet, a cometary satellite, or a cometary ring. If the latter, it will be obvious that, from whatever part of the circumference of the planet the discharge takes place, the ejected matter will necessarily move in the same direction as the axial rotation. More- over, if the discharge continued without interruption during one or more rotations of the planet a complete ring of discrete bodies would be formed in accordance with the accepted theory and observations. It will be further evident from the three orders of cometary discharge specified above, the formation of the outer ring A preceded that of the next inner ring B, as shown by the interval of 2,585 miles of clear space between them. That the second ring was formed some time sub- sequently to the first, is highly probable from the long period of intermittent discharges observable in terrestrial volcanoes, and also in celestial explosive action, of which there are abundant instances in planetary volcanoes and variable stars. That the third and dusky ring C of Saturn represents its last and final effort of cometary evolution is shown by the wide separation of the discrete bodies of which the ring C is composed, and further indicated by its semi- transparency through which the body of the planet is distinctly visible. I have not included in the table of distances the now well-recognized subdivisions of the exterior ring A and of the dusky ring C, so distinctly seen in the photographs, but they are sufficiently definite for a measurement to be taken of their width, which is approximately 230 miles. 1 8 Wilde, Origin of Conietary Bodies and Satunis Rings. The thickness of the rings is difficult to determine on account of the great distance of Saturn from the earth, and has been estimated by Herschel as not exceeding 250 miles. Assuming this value to be approximately correct, the vent in the crust of the planet through which the matter of the rings was ejected may not have been larger than those from which it is assumed the outer satellites of Saturn and Jupiter were also ejected. The polar compression of Saturn is well determined by the photographic method when the edge of the ring alone is visible, and is in the ratio of 10 to 1 1 of the equa- torial diameter. The value of the compression from good observations varies between and 9"02 1 01 9 Turning now to the times of revolution of Saturn's rings respecting which there are wide differences of opinion, arising from the fact that there are no distinctive marks on their surfaces from which their rotations can be determined. Laplace and also Herschel were content to consider the rings as one body, and both assigned the period of its rotation to be 10 hours 32 minutes, as being the time of a satellite revolving at the same distance as the middle of its breadth. Later investigators have, however, found it necessary to recognize, from the discrete constitution of the rings, the different times of revolution of their outer and inner circumferences, but have still treated them as one body, and assigned a period of 12 hours 5 minutes for the outer circumference, and 5 hours 50 minutes for the inner edge of the dusky ring C. From the fact that the ring A is separated from the inner ring B by a clear space of 2,585 miles, the time of Manchester Memoirs, Vol. Iv. (1910), No. 1. 19 its revolution may be determined independently of the times of B and C. As the ring A is postulated to be the first annular ejection from the planet, its outer edge would be the extreme limit of the ejective force, and it would conse- quently revolve in the same time as a satellite at the same distance, in accordance with Kepler's third law. Now the period of Mimas, the first satellite of Saturn, is 22 hours 37 minutes, hence we have for the outer edge of the ring a periodic time of 12 hours 48 minutes ; and ii hours 45 minutes as the time of rotation at the middle of its breadth. Dealing with the second ring B in the same manner, we have for the outer edge a period of 10 hours 9 minutes, and for the middle breadth, 8 hours 24 minutes as the period of revolution. The determination of the time of revolution of the dusky crape ring C presents some difficulty on account of the wide separation of the discrete particles of which it is composed, and its apparently close contact with the interior of the ring B, but as by Kepler's law the time of revolution of the interior of B would be 6 hours 44 minutes, the exterior parts of C may be assumed to revolve at the same rate, and the inner edge of C in 5 hours 15 minutes. From the principle of the transformation of energy it may be rightly inferred that some of the molar motion of the vast assemblage of discrete particles constituting the rings would be converted into heat, with a consequent slow •contraction of their orbits. The observations collected by O. Struve in favour of such contraction have been discussed by astronomers, but without so far arriving at any definite conclusion. 20 Wilde, Origin of Covietary Bodies and Saturn's Rings, The resemblance of Saturn's rings to the Zodiacal Light is briefly indicated by Kant in a short chapter of his ' Theory of the Heavens,' in which he accounts for its origin by assuming that the fire of the sun raises from its surface vapours similar to those which formed Saturn's ring, and by their motion around the sun formed an .expanded plain in the plane of the sun's equator, or in the figure of a convex lens. Modern investigators have since carefully observed this singularly interesting object, and mostly agree that it is a vast accretion of cometary and meteoric particles from outer space and extending beyond the earth's orbit, but none of them, so far as I know, has suggested the interior of the sun as the place from which the Zodiacal substance has been ejected. That cometary and meteoric matter may have contri- buted to the volume of discrete bodies surrounding the sun and extending to some distance within the orbit of Mercury has some degree of probability in its favour, but the extreme tenuity of the outermost parts of the Zodiacal substance, together with its immense distance from the central body, appears to me to be better accounted for on the supposition of its consisting of the lighter elementary substances in a state of extreme sub-division ejected during solar eruptions, as in the instance of the ejection of enormous masses of hydrogen observed by Young which I have already adduced. CORRIGENDUM and ADDENDUM. Page 6 line 18,/^?;- " 9000 million miles " read " 9000 times." onnn v r>. 7S^ I'^n /tnn = ic; c\\ i r\if\ f>r\n c\r\f\ nnilf>Q Manchester Memoirs, Vol. L V. {No. 1), Plate I. CoMETARY Satellites with Retrograde Motion. Manchester Memoirs, Vol. L V. {No. 1). Plate II. Scaled Diagram of Saturn's Rings. Manchester Memoirs, Vol. L V. {No. 1). Plate III. Manchester Memoirs, Vol. Iv. (1910), No ?J. II. Note on Scattering during- Radio-active Recoil. By Walter Makower, M.A., D.Sc, AND Sidney Russ, D.Sc. Received and read November ijtii, igio. In the course of some experiments on the recoil of radium B from radium A, it was found that not only did a surface directly exposed to the recoil stream become active, but surfaces situated outside the direct stream also received active deposit. It was thought that these effects were due to reflection or scatterinij from the surfaces Fig. I. upon which the recoil-atoms fell, and a few preliminary experiments were made to test this hypothesis. The experiments, which were carried out in a high vacuum, were made in the following way. A plate S was mounted as shown in Figure i in such a way that it was outside December j6t/i, igio. 2 Makowek, Scattermg during Radio-active Recoil. the recoil-stream coming from the active wire P, coated with radium A, but so that recoil-atoms reflected or scattered from the copper reflector O could reach it. The distance from the wire to the reflector O was 1*4 cms., and that from the reflector to the surface V2 cms. After an exposure of ten minutes in vacuo, the plate S was removed and found to be active, and the nature of the \^ Fig. 2. active matter on the plate was ascertained by measuring its rate of decay with an a-ray electroscope. After expos- ing a plate for ten minutes to the radium B expelled from the wire, the activity should at first rise and attain a maximum after 27 minutes, and then fall ofl" with time aS indicated by the dotted curve {Figure 2), which has been Manchester Memoirs, Vol. Iv. (1910), No. %. 3 calculated theoretically. It will be seen that curve B, which represents the results of the experiment just described, hardly rises at all, remaining nearly constant at first, and beginning to decay after about 20 minutes. The curve indicates that more than half of the active matter reaching S was radium C, and not radium B. This result can be explained if, when the radium B impinges on the reflector, a small portion of it is scattered on to S, but the greater part remains on the reflector, and subse- quently gives rise to radium C, a small fraction of which is then directly projected on to the plate S. That the admixture of radium B with radium C on S is to be attributed to reflection is probable, since the matter reach- ing a surface by direct radiation from a wire coated with radium A consists only of radium B. An experiment was performed under these conditions, and the decay curve of the activity collected on a surface after an exposure of ten minutes to the radium A was obtained. The points lying on the curve A {Figure 2) were determined in this way, and we have seen that the curve itself was obtained by calcu- lation for these experimental conditions. In an experi- ment in which a plate was situated so as to receive radium B from a source of radium A, only after a number of reflections, the proportion of radium C reaching the plate was even greater than in the case already cited. The fact that in the case of a single reflection considered above, radium B and radium C reached the plate S in almost equal proportions was a little surprising ; for it has been shown that when a surface is coated with radium B, under normal conditions the number of atoms of radium C which succeed in escaping from the surface by recoil is only of the order of one thousandth of the total number formed.* The composition of the activity on the plate S * Makower & Russ, r/iiL Mag., Jan., J910. 4 Makower, Scattering during Radio-active Recoil. can therefore only be explained either if the quantity of radium B reflected at O is very small, or if the chances of recoil are greater under the present experimental con- ditions than in the previous experiments. The latter explanation seems to be the correct one, for we have seen that radium B and radium C reach the surface S in almost equal proportions, and the a-ray activity of the plate S was found to have about -^^^ the activity of the surface Q when tested 20 minutes after the recoil from the wire P had ceased. Now it can be calculated from these facts that, if a small fraction x of the radium B recoil-atoms reaching Q are reflected on to the plate S, the fraction of radium C recoil-atoms subsequently reaching S to the total number formed on O must be about lo.r. Taken in conjunction with the fact that the activity of O was only twenty times that of S, this result leads to the conclusion that the proportion of radium C atoms which succeed in recoiling from the surface O is greater than the fraction (one thousandth) previously obtained. Though it is not possible to be quite sure of this deduction from the above evidence, the conclusion is not unreasonable since the atoms of radium B deposited from the wire P by recoil are lightly distributed over the surface Q without any risk of being covered by surface films as might easily be the case with any other method of deposition. The whole question of the scattering of recoil-atoms is at present receiving more careful examination. ]\TancJiestey Memoirs , Vol. /:-. (1910), No. 3. III. The Development of the Atomic Theory : (2) The various Accounts of the Origin of Dalton's Theory. By x^NDREW NOKMAN MELDRUM, D.Sc. (Carnegie Kcsearrh Felloiv). (Communicakd by Professoi- H. B. Dixo/i, M.A., F.R.S.) Received June, igio. A'cad Novetnher ist, igio. The origin of Dalton's theory remains one of the outstanding problems in the history of chemistry. Yet the amount of material at hand for the study of the subject is considerable. Dalton's note-books, discovered within the last twenty years in the rooms of the Man- chester Literary and Philosophical Society, contain material of the highest value for the purpose. Also, there are on record important accounts of the genesis of the theory by three different persons. One is given by William Charles Henry, another by Thomas Thomson, and another by Dalton himself Although there are yet other accounts in existence, these three are the only ones that need be considered in detail here. One of the principal results of this paper is to show that these various narratives came, originally, from Dalton himself. In the nature of the case, this is what was to be expected. At the same time the discrepancies between these accounts have to be explained. In the course of the paper it will become more and more evident that the person responsible for them is Dalton. December lyth, igio. 2 Meldrum, Development of the Atomic Theory. I. The Itifliience of J. B. Richter. William Charles Henry held a conversation with Dalton on the subject of the origin of the theory, in which special importance was given to the influence of J. B. Richter. " The speculations which gave birth to the atomic theory were first suggested to Mr. Dalton by the experiments of Richter on the neutral salts ... a table was formed exhibiting the proportions of the acids and the alkaline bases constituting neutral salts. It immediately struck Mr. Dalton that if these saline com- pounds were constituted of an atom of acid and one of alkali, the tabular numbers would express the relative weights of the ultimate atoms. These views were con- firmed and extended by a new discovery of Proust,"' &c. This narrative received strong support from William Henry (the father of W. C. Henry), who held more than one conversation with Dalton on the subject. The following is part of a minute, dated February 13, 1830, of one of these conversations : — " Confirmed the account he before gave me of the origin of his speculations leading to the doctrine of simple multiples, and of the influence of Richter's table in exciting these views."^ The Henrys, father and son, are entitled to the fullest credence in this matter. Their acquaintance with Dalton was more intimate than that of any other man of science, Peter Clare excepted. W. C. Henry was in turn the pupil, the friend and the biographer of Dalton. In the preface to the Biography, he mentions with just pride Dalton's " almost lifelong friendship with my father, never shadowed by even a passing cloud " ; and he refers also to " his early favourable notice of and unceasing benevolent regard towards myself, thoughtfully mani- ' W. C. Henry, "Memoirs of Dalton," p. 84. - Ibid., p. 63. Manchester Memoirs, Vol. Iv. (1910), No. 14. 3 fested in his last bequest to me of what he had most prized in Hfe." This was the bequest of all his chemical and philosophical instruments and apparatus. Other proofs of this friendship can easily be found. There is the dedication of Dalton's " New System of Chemical Philosophy " (vol. i., Part 2) to William Henry (along with Humphrey Davy), and of Henry's " Elements of Experimental Chemistry" (6th Ed., 1810) to Dalton. Again, Dalton took an opportunity in 1827 of acknow- ledging his friendship with William Henry. " It affords me great pleasure to acknowledge the continued and friendly intercourse with Dr. Henry, whose discussions on scientific subjects are always instructive, and whose stores are always open when the promotion of science is the object."^ There is no room for doubt that the reports of these conversations with Dalton are perfectly authentic. W. C. Henry states that he noted down Dalton's expressions " immediately after each lesson," and the passage which has been quoted, regarding the influence of Richter, is copied, he says, " verbatim from my own journal when his pupil."* Nevertheless, Henry knew there was something wrong. The date of his conversation with Dalton was February 5, 1824, and he says, "on reviewing in con- versation, after the lapse of twenty years, the labours of the past, Dalton himself may have failed in recalling the antecedents of his great discovery in the exact order of sequence"^ Again, the Richter story is strongly challenged by Thomas Thomson. "When I visited him in 1804 at Manchester both Mr. Dalton and myself were ignorant of " "New System of Chemical Philosoph}-,'' vol. 2, p. 8, 1827. * Ibid., p. 84. ° Ibid., p. 86. 4 MFLDRU^r, Devdopiuoit of the. Atomic Theory. what had been done by Richter on the same subject." Again, " Nobody knows better than myself that Dalton was ignorant of what Richter had done about ten years before him.'"' This shows conclusively that Dalton said nothing about Richter to Thomson. Now that we have access, thanks to Roscoe and Harden's " New View of the Origin of Dalton's Atomic Theory," to the valuable material contained in Dalton's notebooks, we can carry the critical process further than Henry and Thomson did. The notebooks show, as Roscoe and Harden point out, that Dalton had been busily engaged during the year 1803 on the atomic theory, and that he was investigating the non-metallic elements then, and not Richter's acids and bases at all. Dalton's knowledge of Richter can hardly have been due to anyone but Berthollet. Richter's work had been completely ignored till E. G. Fischer gave a resume of it, and thus made it known throughout Germany. Ber- thollet, by quoting this resume at the end of the " Essai de Chimie Statique," made Richter known throughout Europe. In the " Essai " Berthollet opposes Dalton's theory of "mixed gases," but Dalton made no reply till 1808 in the " New System of Chemical Philosophy." This helps to date his knowledge of Richter. If Dalton was slow to read new books, he was prompt in replying to criticisms of his theory. He kept up the defence of it in a series of papers which came to an end about October, 1805, without any mention of BerthoUet's objections having been made. It was presumably subsequent to this date that Dalton read the "Essai," and learnt of Richter's work. In the note-books the date of the earliest reference to Richter is April 19th, 1807.'' There is really no room for doubt that *■' Pi-oc. Phil. Soc. Glasgow, vol. 2, pp. 86, 88, 1845-6. ' Roscoe and Harden, " New View of ^tlie Origin of Dalton's Atomic Theory,'" p. 79 ; see also pp. 7-10, 46, 91-94. Munches ley Monoirs, Vol. Iv. (191OJ, No. %, 5 Dalton's declarations in 1824 and 1830 to one and the same effect regarding the influence of Richter must be set aside.- 2. The Conipositio}i of Marsh-gas and Olefiant Gas. Thomas Thomson says that the theory first occurred to Dalton during his investigation of marsh-gas and olefiant gas. The discovery of the composition of these gases led to the discovery of the law of multiple propor- tion, and the theory was then devised in order to explain the law. His exact words are : — " Mr. Dalton informed me that the atomic theory first occurred to him during his investigations of olefiant gas and carburetted hydrogen gas, at that time imperfectly understood, and the constitution of which was first fully developed by Mr. Dalton himself It was obvious from the experiments which he made upon them that the con- stituents of both were carbon and hydrogen, and nothing else. He found, further, that if we reckon the carbon in each the same, then carburetted hydrogen contains exactly twice as much hydrogen as olefiant gas does. This deter- mined him to state the ratios of these constituents in numbers, and to consider the olefiant gas a compound of one atom of carbon and one atom of hydrogen ; and car- buretted hydrogen of one atom of carbon and two atoms of hydrogen. The idea thus conceived was applied to carbonic oxide, water, ammonia, &c., and numbers were given representing the atomic weights of oxygen, azote, &c., deduced from the best analytical experiments which chemistry then possessed.'"^ This narrative has passed muster for many years, and is better known than any other. It was accepted with ■" Roscoe and Harden, loc. <■//. " Tluimas Thomson, " History of Chemistry," vol. 2, p. 291. 6 Meldrum, Development of the Atomic Theory. reservations by W. C. Henry'" and Angus Smith", and by Roscoe and Schorlemmer^' without objection. Owing to the large circulation of Roscoe and Schorlemmer's book, this version of the origin has decided the opinion of the generality of chemists. There is, nevertheless, the best reason for thinking that marsh-gas and olefiant gas did not have the effect which it assigns to them of leading to the theory. Indeed, in i8ii, Dalton connected the theory in its early days with the oxides of nitrogen : — " I remember the strong impression which at a very early period of these inquiries was made by observing the proportion of oxygen to azote, as i, 2, and 3, in nitrous oxide, nitrous gas, and nitric acid, according to the experiments of Davy."^° Thomson must have seen the necessity of aban- doning the marsh-gas and olefiant gas story, for he said in 1850 : — "Dalton founded his theory on the analysis of two gases, namely, protoxide and deutoxide of azote." '■' Dalton's work on marsh-gas appears in the note-book under date 6th August, 1804. Roscoe and Harden'^ point out that he had been busily engaged on the theory the year before. He had even arrived at the fundamental ideas of his system, and had constructed a table of atomic weights by September 6th, 1803. Obviously, Thomson's account of the origin of the theory is untrustworthy, inasmuch as marsh-gas and olefiant gas had no part in the matter. The question arises, who is responsible for the error, Thomson or Dalton ? Before answering this question it is necessary '" " Memoirs of DalLon," p. So. ^ ' " Memoir of Dalton,"' p. 231. '- '• Treatise on Chemistry, Non-metallic Elements,'' p. 36, 1877. ** Nicholsoiis Joiii-ii., vol. 29, p. I43, 181 1. ' ■' Proc. Pliil. Soc. Glasgow, vol. 3, p. 140, 1850. 1^ Op. cit., p. 28. Manchestef Memoirs, Vol. Iv. (1910), No. 3. 7 to consider carefully the relations between the two men and the circumstances under which Thomson's narrative arose. Thomson, unlike the Henrys, was not a personal friend of Dalton. He had made an adverse criticism of a certain theory of which Dalton was the author, and the author had made a stiff rejoinder/"' He thereupon paid a visit to Manchester with the object of arriving at a full understanding of the matter in question. The date of the interview was August 27th, 1804, ^"d it was then, b\- a fortunate accident, that Thomson learnt of the chemical atomic theory of Dalton. Again, it is certain that Thomson and Dalton were not subsequently in frequent communication with one another on the subject. The sketch of the theory, which Thomson published in 1807, was accompanied by the note : — " In justice to Mr. Dalton, 1 must warn the reader not to decide upon the notions of that philosopher from the sketch which I have given, derived from a few minutes conversation, and from a short written memorandum. The mistakes, if any occur, are to be laid to my account, and not to his ; as it is extremely probable that 1 may have misconceived his meaning in some points."'' Nevertheless, this footnote errs on the side of caution. Thomson's sketch of the theory, giving the first account of it ever printed, was based on notes of what Dalton told him, made during the interview, and only one phrase in it is open to objection. He showed both zeal and care in the matter, for it strongly interested him. In the "History of Chemistry," published in 1831, Thomson says : — " I wrote down at the time the opinions which he offered, and the following account is taken ' '^ See Nicholson' s Joitni., vol. 8, p. 145, 1804 ; and Annals of Philo- sophy, vol. 4, p. 65, 1814. ^^ Thomas Thomson, "System of Chemistry," 3rd Ed., vol. 3, p. 425, 1807. S Meldrum, Development of the Atomic Theory. literally from my journal of that date.'"* Then comes an account of the atomic theory, and on that there follows the passage already quoted, connecting" marsh-gas and olefiant gas with the genesis of the theory. Here the question arises, is all this taken from the journal, both the sketch of the theory and of how the theory arose? Only an examination of the journal can settle this point, but I have not succeeded in ascertaining where it is kept, if, indeed, it is still in existence. It must be admitted also that Thomson seems to become more and more positive regarding the genesis of the theory as time goes on. The account which I have been considering was published in 1831. Six years earlier he had advanced the same account in a more hesi- tating way : — " Unless my recollection fails me, Mr. Dal- ton's theory was originally deduced from his experiments on olefiant gas and carburetted hydrogen.'"'' Yet there is no intrinsic improbability that Thomson's recollection is correct. One cannot doubt that during the interview Dalton was much less interested in the question of the origin than in the theory itself If Thomson inquired about the origin, Dalton may have made the inquiry an opportunity of expounding the theory in terms of its latest triumph, namely, the composition of marsh-gas and olefiant gas. 3. The Amended Theory of^' Mixed Gases" There remains for consideration the account which Dalton gave in a lecture (the 17th ofa series) at the Royal Institution of London, on the 27th January, 18 10. The '" Thomas Thomson, " liisloiy of Chcmisliy," vol. 2, p. 287. '■'Thomas Thomson, " An Attempt to Estabhsh the First Principles of Chemistry by Experiment," vol. i, p. 11, 1825. Manchester Memoirs, Vol. Iv. (1910), No. 3. 9 notes for it still exist in his own handwriting, and were found, along with his notebooks, in the rooms of the Man- chester Literary and Philosophical Society. He begins by discussing his physical atomic theory, which aimed at explaining the diffusion of gases. He entertained two diffusion hypotheses, the first of which originated in 1801, while an amended hypothesis, he says, was formed in the year 1805. He had not at first "contemplated the effect oi difference of size in the particles of elastic fluids." On consideration, he " found that the sizes must be different," and subsequently arrived at a different explanation of the mechanism of diffusion from the one he at first suggested. He then introduces the subject of the chemical atomic theory : — " The different sizes of the particles of elastic fluids under like circumstances of temperature and pres- sure being once established, it became an object to deter- mine the relative sizes and zveigkts, together with the relative ?z«w<^^r of atoms in a given volume. This led the way to the combination of gases . . . other bodies besides elastic fluids, namely, liquids and solids, were subject to investigation, in consequence of their combining with elastic fluids. Thus a train of investigation was laid for determining the number and weight of all chemical elementary principles which enter into any sort of com- bination one with another." ■" This narrative is certamly right on a vital matter. It recognises that Dalton had been using a physical atomic theory, from which he passed to a chemical one. Here there is a common ground of objection to the com- munications made by Dalton to Thomson and Henry respectively. They both ignore the connection, which certainly existed, between the physical and chemical theories. Thomson did not feel this defect, but Henry ■-" Roscoe and Harden, Op. cit., pp. i6 — 17, lo Mrldrum, Development of the Atomic Theory. did. While not denying the influence of Richter, he sums up the evidence on the subject as " unequivocally demon- strating the genesis of the atomic theory as a general ph)'sical conception from the study of matter in the aeriform condition, and its first practical application in chemistry to gaseous bodies, and emphatically to such as combine iyi multiple proportions."'^ There is no question here of extraordinary insight and discernment on Henry's part. He has simply considered the use Dalton had made of the physical atomic theory previous to forming a chemical one. Roscoe and Harden have not paid sufficient attention to this. They say " It is . . . . well known that Dalton was an ardent adherent of the Newtonian doctrine of the atomic constitution of matter .... It now appears that it was from this physical standpoint that Dalton approached the atomic theory, and that he arrived at the idea that the atoms of different substances have different weights from purely physical considerations."-" There is really not sufficient justification for Roscoe and Harden's suggestion that they had found in Dalton's narrative a new view of the genesis of his atomic theory. The view is to be found in Henry, and might be formed by any person who should read with understanding Dalton's " Essay on the Constitution of Mixed Gases," which was written in i8oi, and published in 1802. There is, however, a fundamental objection to Dalton's narrative. It has a deceptive appearance of being historical. Dalton was a pioneer of science, and a pioneer is a man who must make many mistakes and experience many failures. He has taken a number of different scientific movements and marshalled them, so that they are invested -•' W. C. Henry, (9/.. at., p. 84. ■-'-' 1-loscoc and Ihirflen, ()/. cit., p. viii. MancJiester Memoirs, Vol. Iv. (1910), No. 3. 11 with the appearance of a deliberate, strategical, irresistible advance. On examination his narrative, in spite of its grand air, is found to throw much less light than it pro- mises on the line of thought and train of investigation which he pursued. It is excessively abstract in tone, and avoids going into details and particulars and instances. It does not tell us what we want to know most, how and when Dalton arrived at the law of multiple proportions, and the part played by the law in the construction of the theory. Information on these matters is what is wanted, and anything else is beside the point. Yet there is one novel element in Dalton's account. This is the suggestion that the formation of the chemical atomic theory took place subsequently to the amendment of the diffusion theory. But, as the notebooks show, the chemical theory was formed in 1803. Hence, Roscoe and Harden conclude that iSo5,the date which Dalton assigns to his amended diffusion theory, should be 1803.^ Reasons will be given later, in a paper on Dalton's physical atomic theory, for thinking that the narrative is doubtful on the only point on which it presents any novelty. Conclusion. There are in existence yet other accounts of this matter. One is given by Dalton's pupil, Joseph A. Ran- some,^* and another by Dalton himself. This was in the lecture which he delivered to the members of the Mechanics' Institute in Manchester on October 19th, 1835.''^ The main feature, which ^/Z the accounts have in - => op. tit., p. 25. -* W. C. Henry, Op. dt., pp. 220-222. -* Manchester Times, October 25, 1835. 12 Meldrum, Developme7it of tJic Atomic TJieory. common, is that each originated with Dalton. Thomson's narrative and Henry's and Ransome's were based on conversations with him, and there is no ground for impugning their accuracy any more than his good faith. The natural explanation of the existence of so many and various accounts is that Dalton was simply deficient in historical instinct. He did not perceive the difference between describing the genesis of his theory and ex- pounding the theory itself. A man who makes history, as Dalton did, need not be a good historian. The account of the origin of the chemical theory in his own handwriting is no more satisfactory than the others which came from him at second-hand. Apparently, Dalton never had in his mind a precise view of how the theory developed, and when invited to give one he produced, on the spur of the moment, an account to which he did, or did not, adhere on the next occasion. Manchester Memoirs, Vol. Iv. (1910), No. 4- IV. The Development of the Atomic Theory: (3) Newton's Theory, and its Influence in the Eighteenth Century. By Andrew Norman Meldrum, D.Sc. ( Carnegie Research Fellow). ( Commu?ncated by Professor H. B. Dixon. M.A., F.R.S.) Received June, jgio. Read November ist, igio. One of the great obstacles to a right understanding of the history of science, is the tendency of writers to let their attention be absorbed by a single individual, who thus engrosses the credit for important ideas and discoveries, to the neglect of deserving predecessors. This method, besides being unjust, gives a distorted view of the progress of science. For instance, Nernst, apropos of Dalton, remarks that the atomic hypothesis " by one effort of modern science, arose like a phoenix from the ashes of the old Greek philosophy"^ This sweeping statement ignores atomic speculation between the time of Lucretius and the nineteenth century. As if the atomic theory of Newton, for instance, were perfectly negligible ! This paper is written in the belief that the atomic tlieory has gone through a process of development from the time of Leucippus up to the present. The main con- clusions are that Newton made a contribution to the said process, that he did so under the influence of Descartes, and that he was, in turn, himself an influence in the eighteenth century. It is therefore divided into two parts : (i) The atomic theory of Newton, and (2) Newton's influence in the eighteenth century. * Nernst, " Theoretische Chemie,"' Sth ed., p. 34. December ijth, igio. 2 Meldrum, Development of the Atomic Theory. I. The Atomic Theory of Neivton. In the seventeenth century the atomic theory is asso- ciated with the famous names of Francis Bacon (1561 — 1626), Rene Descartes (1596 — 1650), Pierre Gassend (1592 — 1655), Robert Boyle (1627 — 1691) and Isaac Newton (1642 — 1727). Bacon recurs to the theory again and again in his philosophical writings, as if fascinated by it. At one time he entertained great expectations from the study of the atoms. " I know not whether this inquiry I speak of concerning the first condition of seeds or atoms be not the most useful of all, as being the supreme rule of art and power, and the true moderator of hopes and works."' This in the " Cogitationes de Natura Rerum," which is regarded as having been composed before the year 1605. I^^t he changed his mind on the subject, tending, as time passed, to become more and more distrust- ful of a priori reasoning. His mature judgment, as ex- pressed in the "Novum Organum," published in 1620, was that the atoms are an unprofitable study. " Men cease not . . . from dissecting nature till they reach the atom ; things which, even if true, can do but little for the welfare of mankind."' Boyle, in this country, was the exponent of the atomic theory who brought it into repute. In the year 1659 he urged the "desirableness of a good intelligence between the Corpuscularian Philosophers and the chemists," * and this topic for some time afterwards he made a leading theme in his scientific writings. Within a few years of his first attempt he was able to say that he has "had the happiness - Bacon's Works, ed. by Spedding & Ellis, vol. 5, p. 423. ' Op. cit., vol. 4, p. 68 ; or Nov. Org., I, aphorism 66. * Boyle's Works, ed. by Birch, vol. I, p. 227, 1744. Manchester Monoirs, Vol. Iv. {igio). No. 4t- 3 to engage both divers chymists to learn and relish the notions of the Corpuscular Philosophy, and divers eminent embracers of that to endeavour to illustrate and promote the new philosophy by addicting themselves to the experi- ments and perusing the books of chemists."'' While on this subject, he mentions Descartes and Gassend con- stantly, and other philosophers hardly ever. Descartes believed in the existence of atoms, and at the same time he denied that a void could exist. A subtle fluid occupied the space between the atoms, and even per- meated them. Hence the vortex motion which had been set up in the fluid could not but communicate itself to the atoms. An admirable description of the atmosphere, according to the Cartesian theory, is to be found in Boyle's " New Experiments, Physico-Mechanical, touching the Spring of the Air." "The restless agitation of that celestial matter, wherein these particles [of air] swim, so whirls them round, that each corpuscle endeavours to beat off all others from coming within the little sphere requisite to its motion about its own centre . . . their elastical power is made to depend . . . upon the vehement agita- tion . . . which they receive from the fluid ether that swiftly flows between them."" It is remarkably difficult to find in Descartes so good a description of his theory as thi.s.^ Descartes' denial that a vacuum could exist, it is plain from this, is not to be taken in the crudest sense. He never meant and never said that space is full of matter of the ponderable kind.'' He meant, surely, that in the *• Op. lit., vfil. 2, p. 501. « Op. cii., vol. I, p. 8. ' CEuvres, ed. by Cousin, vol. 5, p. 159-162, 169-170. ^ Clerk Maxwell might well have emphasised this in his comment on "The Error of Descartes," in " Matter and Motion," article xvi. 4 M^L\M<\:'S\, Dere/opjncnt of the Atomic TJieory. absence of ponderable matter, space is occupied by ether, " the celestial matter ; " in short, that " we have no means of producing an ether-vacuum." A more conventional theory is due to the revival, by Gassend, of the Epicurean philosophy. His interest in this philosophy was such that for twenty years he devoted himself to the study of Epicurus, and Lucretius the Epicurean." Gassend sought to connect the atomic theory with both physical and ethical problems, for those were the days when natural and moral philosophy were studied by the same persons. He brought out three books on the subject, between the years 1647 and 1649, one of which, the " Syntagma Philosophiae Epicuri," was well known to Boyle. Boyle learnt of the work through his friend Samuel Hartlib, who wrote to him, in a letter dated London, May 9th, 164S : "Your worthy friend and mine, Mr. Gas- send, is reasonable well, and hath printed a book of the life and manners oi Epiaii us, since your going from here. He hath now in the press at Lyons the philosophy of Epicurus, in which, I believe, we shall have much of his own philosophy, which doubtless will be an excellent work." ^^ There was then, as there is still, a tendency to regard Descartes and Gassend as opponents of one another on the principles of the atomic theory. Boyle mentions some "learned men as more favouring the Epicurean, and others (though but a few) being more inclinable to the Cartesian opinions." However, in one of his essays, he advises Pyrophilus to read the "learned Gassendus,\{\s " For a study of the Lucretian philosophy, see "Lucretius, Epicurean and Poet," 2 vols., by John Masson. Chap, i, vol. 2, is devoted to Gassend, of whom it gives a most interesting account. '" Boyle's Works, ed. by Hirc'n, vol. 5, p. 257, 1744. Manc/iestcr JMcjiioirs, Vol. Iv. (1910), No. 4. 5 little SyntagJiia of Epicurus' philosophy, and that most ingenious gentleman, Mons. Descartes, his principles of philosophy." " He did not see any necessity to ally himself with one party or the other. " Notwithstanding those things, wherein the atomists and the Cartesians differed, they might be thought to agree in the main, and their hypotheses might, by a person of a reconciling disposition, be looked on . . . as one philosophy." ^^ Science has often gained immensely by a wise limita- tion of the problem to be solved. Descartes' theory, that space is pervaded by an ethereal fluid, and that ordinary matter consists of atoms swimming in the ether, is formally complete, and has to be adopted sooner or later. Yet Gassend's theory, which is incomplete, since it ignores the ether, and concentrates attention on the atoms, proved more helpful to science in the first instance. Newton was more inclined to Gassend's way of thinking than to Descartes'. In the " Principia" he would not consider the mechanism of gravitation, and in the course of his atomic speculations he almost leaves out of account the means by which chemical attraction arises. Nevertheless, Newton was influenced by Descartes. The Cartesian natural philosophy was predominant throughout Europe for the most part of the seventeenth century, and, in the eighteenth, it was supplanted by the Newtonian philosophy, as expounded in the " Principia." The two philosophies being opposed to one another, no one apparently has reflected how much Newton may have been indebted to Descartes. The mere fact that Cartesianism was dominant during the seventeenth century means that Newton must have made himself master of that system of nature. Presumably '1 op. fit., vol. I, p. 194. 12 op. cit., vol. I, p. 227-228. 6 Meldrum, Developmoit of the Atomic Theory . then, whatever was sound in Descartes he retauied and assimilated. Boyle and Hooke had studied Descartes, and Newton studied all three. In a letter to Hooke, dated Feb. 5th, 1675/6, on the subject of light, he admits his indebtedness to others. " You defer too much to my ability in searching into this subject. What Descartes did was a good step. You have added much several ways, and especially in considering the colours of thin plates. If I have seen further, it is by standing on the shoulders of giants." ^'" Newton, in his speculaiions on the disintegration of atoms, in Query 31 of the "Optics," had no unusual physical phenomenon in viev.' at the time. He was simply improving on Descartes," whose theory on the subject seems crude enough.'' In contrast to the speculative topic of disintegration, another problem which interested Newton was a perfectly concrete one. This was Boyle's law, made known in the year 1662, that the volume of a given quantity of air is inversely proportional to the pressure. Newton's theory of gravitation was based on the assumption that every particle of matter attracts every other particle. In ex- plaining Boyle's law he made the very different assumption that air is composed of particles which repel one another. This conception of the atmosphere, as being composed of " particles mutually repulsive," was in all probability derived from Descartes. Boyle, in the passage already quoted, where he explains the Cartesian theory, says that in the air, "each corpuscle endeavours to beat off all others from coming within the little sphere requisite to its motion about its own centre." ^•'' Brew.ster's " Life of Newton," vol. I, p. 142. '■' CEuvres, ed. by Cousin, vol. 4, pp. 266-268. ^ ^ I am indebted to my friend, Mr. J. R. Partington, B.Sc, for pointing out to me that Descartes was the source of Newton's ideas on disintegration. Manchester Memoirs, Vol. Iv. (1910), No. 4- 7 Newton proved that the air must obey Boyle's law, if the force of repulsion between its particles were in- versely proportional to the distance between them. He does not mention Boyle, or the air, but puts the matter in the most abstract way, by advancing the following propo- sition : — " If the density of a fluid which is made up of mutually repulsive particles, is proportional to the pressure, the forces between the particles are reciprocally propor- tional to the distance between their centres. And vice versa, mutually repulsive particles, the forces between which are reciprocally proportional to the distance between their centres, will make up an elastic fluid, the density of which is proportional to the pressure." ^^ Newton does not draw any inference as to the nature of the atmosphere. " All these things are to be under- stood of particles whose centrifugal forces terminate in those particles that are next them, or are diffused not much further. We have an example of this in magnetical bodies. .... Whether elastic fluids do really consist of particles so repelling each other, is a physical question. We have here demonstrated mathematically the property of fluids consisting of particles of this kind, that hence philosophers may take occasion to discuss that question." This proposition, along with its proof in the " Principia,'' is the earliest instance of the mathematical treatment of the atomic theory. Svante Arrhenius declares that "the atomic theory remained in the hypothetical state for about 2,300 years, as no quantitative conclusions were drawn from it till the time of Dalton." '" This statement entirely ignores Newton's explanation of Boyle's law in terms of atoms, as well as certain workers in the eighteenth century, who were under Newton's influence. ^'^ " Principia," Book 2, prop. 23. ^^ Arrhenius, " Theoi'ies of Chemistry, Eng. trans., p. 15. 8 Melurum, Developuicni of the Atomic Theory. II. Netv ton's Influence in the Eighteenth Century. In the last quarter of the eighteenth century a very- remarkable attempt at an atomic theory was made by two Irishmen, by name Bryan Higgins and William Higgins. The object of the second and concluding part of this paper is to show that the theory advanced by Bryan Higgins and amplified by William Higgins can be under- stood only when regarded as springing, under the peculiar conditions of the time, from Newton's theory. These conditions were (i) the knowledge, due to Priestley, of different kinds of gases, and (2) the new light which Lavoisier threw on chemical composition consequent on Priestley's discovery of oxygen. The senior of the two men,'" Bryan Higgins (1737- 1820) was self-taught in chemistry, and his career proves him to have been the best all-round man among the English-speaking chemists of his day. His " Experiments and Observations concerning Acetous Acid" (1786) is a record of a very thorough investigation in the field of organic chemistry, in the course of which he discovered the substance acetamide. As a technical chemist his reputation was wide. He spent about four years (1797- 1802} in the West Indies, investigating the manufacture of Muscovado sugar and rum. He was a pioneer in the practical teaching of chemistry, and gave instruction in the subject for some twenty-three }-ears (1774-1797) in his School of Practical CJieniistry in Greek Street, Soho, London. His minor discoveries include that of the musical note which can be got on burning a jet of hydrogen in air (1777}. '* For fuller information regarding them, see Brit. Assoc. Rep., Dublin meeting, 1908, p. 668, and New Ireland Review, 1910, n.s., vol. 32, pp. and 350-364. Maiidicster Memoirs, Vol. Iv. (1910), No. 4- 9 His most important publication, in connection with the atomic theory, is a " Philosophical Essay Concerning Light" (1776). This essay is very different from what it purports to be. It contains only a fragment — all that was ever published — of the essay on light that Higgins had designed. The major part of the book is simply an expansion and exposition of a " Syllabus of Chemistry," which he had published earlier, in 1774 or 1775, and which is also prefixed to the Essay. Higgins had gone to Newton for inspiration : the "Philosophical Essay" is full of quotations from the " Opticks." Nor need there be any wonder at Higgins making his approach to the study of light by way of chemistry, since Newton's views on chemical subjects are to be found in the "Opticks" more than in any other of his books. The discovery of new facts always gives a stimulus to speculation. The impulse in Higgins' case came from Joseph Priestley, who showed in the year 1775 that the alkaline substance ammonia, and various acids, hydro- chloric, for instance, can exist in the gaseous state. Higgins thereupon proceeded to adapt the Newtonian conception of a gas to the processes of chemistry. Gaseous particles of the same kind were " mutually repul- sive," but what should happen in case acid and alkali were brought together? Higgins said that the acid particles and the alkaline attracted one another, and formed a neutral salt by combining /^^f/^V■/(^ with particle. Higgins laid great stress on this force of repulsion between particles of the same kind. He thought an acid and an alkali must combine with one another in one proportion only, a combination of two particles of acid and one of alkali, or two of alkali and one of acid, being precluded, because the two similar particles 10 Meldrum, Development of tJie Atomic TJieory. must repel one another. On this line of thought he finds the answer to his own question : — " Why do many salts crystallise nearly neutral in a liquor con- taining a superabundant quantity of acid and \sic'\ of alkali?" Further, on the supposition that particles of water and of acid attract one another, as also particles of water and of alkali, he thought he could account for the water of crystallisation found in many salts, so he explains " why much water doth combine in the crystals of most neutral salts, and why this water of crystallisation separates from the superfluous acid or alkali, and in- troduces little or none of either into the crystals." '' In short, on the basis of Newton's theory of a gas, Bryan Higgins taught that chemical combination takes place between acid and alkali in a definite and single proportion. He went little further, if any, with these speculations. His progress must have been greatly hampered by his belief, to which he adhered till about the year 1792, in the phlogiston theory of chemistry, and by his belief in the existence of seven chemical elements, namely, earth, water, air, acid, alkali, phlogiston and light. William Higgins (i769?-i825) was trained in chem- istry by his uncle. He assisted Dr. Beddoes in the teaching of chemistry at Oxford (1787), and acted as chemist to the Apothecaries' Hall of Ireland (i 791 -1795), and then to the Royal Dublin Society (1795-1825). He was a Fellow of the Royal Irish Academy and of the Royal Society of London. He did not long suffer from the disadvantages of the phlogiston theory, for he was one of the first to ^^ Biyan Higgins, "A Philosophical essay concerning Light," pp. 201- 208, 212-213. Mancliester Memoirs, Vol. Iv. {igio), No. 4. ii abandon it — in 1785, he says — and was absolutely the first to write against it in the English language. His " Comparative View of the Phlogistic and Anti-phlogistic Hypotheses" (1789) is primarily a refutation of the phlogiston theor}'. Incidentally, it shows that he had been carrying on experimental work of his own, and also that he had improved on his uncle's speculations. Out of atoms and molecules he fashioned a theory of chemical combination and chemical dynamics as well, so that his book is remarkable as containing the first attempt at a comprehensive system of chemistry, based on the atomic theory. William Higgins regarded the atom of a gas as a hard particle surrounded by an "atmosphere of fire.""" He believed firmly that chemical combination occurs in definite proportions, and supposed that it occurs, in the first place, atom with atom. He regarded the molecule of water as formed by the linking of one atom of hydrogen with one of oxygen. " Water is composed of molicules formed by the union of a single ultimate particle of dephlogisticated air to an ultimate particle of light inflam- mable air . . . they are incapable of uniting to a third particle of either of their constituent particles."^ In short the formula OH expresses his conception of the molecule of water. William Higgins was better acquainted with the facts of chemical composition than his uncle, for he did not believe in phlogiston, and he recognised oxygen as one of the elements. He was aware of a number of cases in which elements combine in more than one proportion, and in such cases continued to apply the atomic theory. ** " Comparative View of the Phlogistic and Antiphlogistic Hypotheses," pp. 14, 37, 81, 133. Ibid., p. 37. 12 Meldrum, Development of the Atomic Theorr. He thought an element R must form oxides in the order RO, RO„, RO3, etc. Thus he regarded sulphurous acid virtually as SO, and sulphuric acid as SOo."'' He recog- nised five oxides of nitrogen, and regarded them as NO, NO„, NO.„ NO4, and NOe."' These ideas of chemical composition are based on the assumption that similar atoms repel one another, an assumption which is also the basis of his system of chemical dynamics. His argument was that because of this force of repulsion, the compound RO is more stable than RO2, RO, than RO,., and so on. The line of thought thus opened by the Higginses afterwards proved extremely valuable, but it was not followed up at the time. William Higgins' book, pub- lished in 1789, and re-published in 1791, was read as a contribution to the phlogiston and anti-phlogiston con- troversy. That was the absorbing topic in science then, and nothing else could be duly attended to. The history of this eighteenth century movement proved a difficult problem in the succeeding century. It occupied the attention at different times of such persons as William Charles Henry, R. Angus Smith, and, in collaboration, Roscoe and Schorlemmer. There was also a long and doubtful controversy regarding the relative merits of William Higgins and John Dalton, the discussion of which is left to a future paper. Angus Smith's estimate of Bryan Higgins is a vastly different one from that advanced in this paper. His main conclusions are, that Bryan Higgins' " opinions on atoms might have been held by the ancients,"'* and " that his theory was not clear, or he would have been led by it to --Ibid., pp. 36-37. •'" Ibid., pp. 132-135, 165. ■^* R. Angus Smith, "Memoir of Dalton,'' p. 175. Manchester Memoirs, Vol. Iv. {\gio), No. 4. 13 decide on the necessity of fixed composition as a result. But we obtain no results affecting chemical philosophy "'^ In this paper I have shown that Bryan Higgins' theory, far from being " ancient," is a development of Newton's, and that instead of his theory being obscure, and leading to confused ideas regarding chemical composition, it led to a view of the doctrine of fixed proportion, of which the fault was that it was too narrow and rigid. This difference of opinion, great and hopeless as it may seem, admits of the simplest explanation. Smith's estimate is based upon the" Syllabus" of the year 1775, and upon certain incidental remarks on atoms which he found in the book on "Acetous acid." He was not acquainted with the "Philo-sophical Essay on Light," which assuredly is not the place where one should expect to find the chemical speculations and ideas regarding atoms, of which nevertheless it is full. Had Angus Smith read this book he must have i)erceived the clue to the Higgins' ideas, namely, the connection with Isaac Newton. He must then have seen that Bryan Higgins was the first to explain the constant chemical composition of salts in terms of atoms, and that his theory was only too definite and rigid, for it led him to maintain that an acid and an alkali could combine in only one proportion, namely, atom with atom. W. C. Henry, in his estimate of William Higgins, shows the fatal weakness of failing to see the basis of the theory. Having given Higgins' views regarding the atomic composition of the oxides of nitrogen, he remarks : " It is evident that Mr. Higgins was guided by no fixed and uniform principle, in assigning the atomic constitution of the above compound bodies."-'^' This verdict also •-» Ibid., p. 173. '-'• W. C. Henry, " Memoirs of Daltoii," p. 77. 14 Meldrum, Development of tlic Atomic Theory. must be set aside. No great penetration of mind is required to divine "the fixed and uniform principle" on which Higgins proceeded in assigning the atomic composition of substances. Although he does not himself mention Newton, there is no room for doubt that Newton's conception of "particles mutually repulsive" w^as the germ of the theory. Bryan Higgins, who was a student of Newton, made use of this conception, and he communicated it to his nephew. The indebtedness of the nephew to the uncle is as plain as the indebtedness of the uncle to Newton. There remains now for consideration a remark by Roscoe and Schorlemmer, that "all upholders of an atomic theory" previous to Dalton, "including even [William] Higgins, had supposed that the relative weights of the different elements are the same."-'^ This is a sweeping assertion, of which no proof has ever been offered. One can hardly believe that Newton expressed such an opinion, and it is certain that William Higgins did not. Regarding the oxidation of tin, he supposed that lOO grains of the metal may combine with 7|- or with 15 grains of oxygen.'""^ But since he held the oxidation series of an element to be RO, RO,, RO., etc., his figures for tin mean that the atom of the metal was supposed to be much heavier than one atom, or even two of oxygen. Possibly Roscoe and Schorlemmer's statement is based on the case of oxygen and sulphur, which Higgins held to have the same atomic weight. But this conclusion of his depends for one thing on the supposition that the molecule of sulphurous acid (the substance SO2, not H.SOg) is com- posed of one atom of each element, and for another on -" Koscoe and Schorlemmer, " Non-Metallic Elements," p. 35, 1905. "■"* "Comparative View,'" p. 275. Manchester Mei)ioirs, Vol. Iv. (19 lo), No. 4. 15 the experimental fact that the acid is formed by the union of equal weights of the two elements. Higgins proved, quite correctly on his supposition, that the atomic weights of sulphur and oxygen are equal. But proof and assumption are two very different things. Surely it is one thing to prove a result in a particular case, and quite another to assume the result in general. Manchester Memoirs, Vol. Iv. ( 1 9 1 1 ), No. 5- V. The Development of the Atomic Theory : (4) Dalton's Physical Atomic Theory. By Andrew Norman Meldrum, D.Sc {Carnegie Research Fellow). (Communicated by Prof. H. B. Dixon, Af.A., F.R.S.) Received October, igio. Read January loth, igii. In the opinion of the author, many of those who write about Dalton let their attention be engrossed too much by his chemical work. For, in order to understand even the chemical work, it must be kept in mind that Dalton began his scientific career as a meteorologist, that this led him to become a student of physics, and that he took up the study of chemistry subsequently. The following paper shows that Dalton's physical atomic theory was the first great achievement of his career. It was based on his experimental work, and theory and work together, as soon as published, aroused, in his own words, the " attention of philosophers throughout Europe." The physical atomic theory, otherwise the theory of " mixed gases," is specially interesting because it marks a stage in the development of Dalton's ideas. Both it and the experiments connected with it arose out of the meteorological observations and studies of his early life. It reveals him as a student of Newton, and as the up- holder of a physical atomic theory years before he formed the chemical one. The present paper is divided into three parts : — I. Dalton's theory of " mixed gases "; II. The beginning and course of Dalton's experimental work ; III. The two forms of the physical atomic theory and the dates of their origin. March yi/i, igii. 2 Meldrum, Development of tJie Atomic Theory. I. DaLTON'S theory of " MIXED GASES." The question at issue. One of the burning questions in science, at the begin- ning of the nineteenth century, was that of the constitution of " mixed gases." The question could hardly have been discussed much earlier, much less been settled, because the existence of gases, different from atmospheric air and from one another, had not been fully recognised till after the discovery of oxygen in 1774. The properties of gases are accounted for now by the Kinetic Theory, but this was not established till after the middle of the century. Apart from this theory, men of science explained matters as best they could. The problem naturally arose in connection with the atmosphere, the nitrogen and oxygen of which, although they have different specific gravities, do not separate from one another. Two opinions, says Dalton, arose on this matter : the one supposed the two fluids were " merely mixed together, but assigned no reason why they do not separate . . . . The other supposes a true chemical union to exist between the two, and thus obviates the difficulty arising from the consideration of specific gravity.^ " The first of these opinions was held by a few isolated indi- viduals. Strange as it must seem now, the chemical explanation of diffusion was not only widespread amongst men of science, but was quite the predominant one. The germ of Dalton s theory. Dalton had early shown a tendency in the direction of a mechanical explanation of the state of the atmosphere. The " Meteorological Observations and Essays " published in i793CGntains, as he pointed out many years afterwards, "^Manchester Memoirs, [i], vol. 5, p. 538, 1802. Manchester Me7Hoirs, Vol. Iv. {igii), No. ^. 3 " the germs of most of the ideas which I have since expounded more at length in different essays, and which have been considered as discoveries of some importance. For instance, the idea that steam or the vapour of water is an independent elastic fluid .... and hence that all elastic fluids, whether alone or mixed, exist indepen- dently."' He was probably influenced most by Deluc in forming this opinion, but other persons, including Bryan Higgins and Pictet, had expressed views more or less the same as Deluc's. Da/ ton's theory of mixed gases. Thus Dalton had early regarded the constitution of mixed gases from the physical point of view. In the year 1801 he formed a precise theory of his own, which he explained and maintained publicly. The paper in which he describes it, forms one of the set of four experi- mental essays, which, Dalton himself said, " drew the attention of most of the philosophers of Europe." He put his theory in the following way : " When two elastic fluids, denoted by A and B, are mixed together, their is no mutual repulsion amongst their particles, that is, the particles of A do not repel those of B, as they do one another." ' At first the doctrine was not understood, and Dalton had to make further efforts to throw light upon it. His hypothesis meant that while gaseous particles of the same kind repelled one another, there were no forces, whether of repulsion or attraction, between particles of different kinds. Particles of one kind could offer only a passive resistance to the motion of another kind of particles, and acted only as temporary obstacles, in the same way as the pebbles in a stream - " Meteorological Observation and Essays," 2nd Ed., p. v. (1834). ^ Manchester Memoirs, [i], vol. 5. p. 536, 1802. 4 Meldrum, Development of the Atomic Theory. impede the flow of water. Hence, if two gases were brought together, they were found, sooner or later, to be uniformly mixed. Dalton and the diffusion of gases. After the theory had been explained, Dalton deemed it necessary to make new experiments on the diffusion of gases. Priestley, who originally drew attention to this phenomenon, was inclined to think it accidental in its nature. He thought that if " two kinds of air were put into the same vessel with very great care, without the least agitation that might mix or blend them together, they might continue separate."* Dalton's experiments, made with the simplest of apparatus, proved, in his own words, " the remarkable fact, tJiat a lighter elastic fluid ca)inot ?-est upon a heavier''^ The importance of this work, by which he established diffusion as a genuine property of gases, was recognised by Berthollet, who carefully repeated it." Dalton was evidently much gratified by the agree- ment between his theory and the facts of diffusion. He concludes his memoir on diffusion with a note of triumph : — " The facts, stated above, taken together, appear to me to form as decisive evidence for that theory of elastic fluids which I maintain, and against the one commonly received, as any physical principle which has ever been deemed a subject of dispute, can adduce."^ Dalton^ s theory and the vapour of ivater. Obviously, a special case of the mixed gases question is that of the water vapour in the atmosphere. The * "Experiments and Observations, &c.," abridged, vol. 2, p. 441. ^ Manchestei- Memoirs, [2], vol. I, p. 260, 1805, 0 M^m. cCArceuil, vol. 2, p. 463, 1809. ' Manchester Memoirs, [2], vol. i, p. 270, 1805. Manchester Mejiioirs, Vol. Iv. (191 1), No. 5. 5 ^general, though not the universal opinion was, that this vapour was present in a state of combination with the air. The evaporation of water was thought to be an act of ■chemical combination between air and water, whilst boiling was a physical action. For since the atmospheric pressure prevents water from boiling at ordinary tem- peratures, it was thought that boiling was something ■quite distinct from evaporation, which takes place at all temperatures and pressures of the air. This distinction had received the sanction even of Lavoisier." Dalton's theory had a special bearing on this subject. For the theory meant that the pressure of a mixture of gases is the sum of the respective pressures of the gases in the mixture. Dalton saw that the water vapour in the atmosphere had to be considered in terms of the pressure ■of the vapour. Experimentally he showed that the evaporation of water is proportional to the pressure of the vapour which the water gives off. At any given temperature there is a maximum which this pressure can reach, and water, whether in contact with the air or not, •can evaporate till the pressure of its vapour reaches this maximum and no further. On the other hand, air in which the water vapour is not at this maximum pressure can be cooled till the maximum is reached, and then, on further cooling, the water is deposited as dew. This led to observations of the " dew-point," which Dalton was the iirst to institute. It was thus in the direction of Meteorology that Dalton's theory first bore fruit. In this science, as Play- fair has pointed out, it is easier than in any other to ^' accumulate observations, and more difficult to ascertain principles." At the beginning of the nineteenth century, hy pointing out the significance of the dew-point, Dalton * " Traite Elementaire de Chimie," 3rd ed., pp. 7-1 1, 39, 6 Meldrum, Development of the Atomic Theory. succeeded in transforming hygrometry, and " raising it to. the rank of an exact science." " Dalton's tlieory and Henrfs laiv. Dalton's theory had been only a short time before the world, when it was reinforced in a remarkable way. It was found to have an important bearing on the solubility in water of a gas under various pressures. The study of this subject had been undertaken by William Henry^ already mentioned in the second paper of this series as a friend of Dalton. Henry had discovered the law, which is now called after him, that at a given temperature, " water takes up the same volume of condensed gas as of gas under ordinary pressure." "^ The amount dissolved is propor- tional to the pressure. This, as Dalton pointed out to Henry, is a strong argument in favour of the view that solution is " purely a mechanical effect." If gas, in a state of absorption by water, is retained entirely by the incum- bent pressure, there is no need to call in the notion of chemical affinity. Not only so, but in the matter of the solubility of a mixture of gases, Dalton's theory proved able to sustain a severe enough test. Henry found that each gas dissolved in water as if the others were absent, " Each gas," he concluded, " when dissolved in water, is retained in its place by an atmosphere of no other gas but its own kind." " This is precisely what was to be expected from Dalton's theory. Henry had opposed the theory when it was first made known. He now wrote Dalton a letter, which was read ° See W. C. Henry, " Memoirs of Dalton," p. 226. I'' JVu'I. Trans., p. 41, 1803. ^^ Nicholson s Joiirn. , [2], vol. 9, p. 126, 1804. Manchester Memoirs, Vol. Iv. (191 1), No. 5. 7 before this Society and then published, expressing his entire satisfaction with it. "In the discussions... which took place in the Society on your several papers, the doctrine of mixed gases was opposed by almost every member interested in such subjects, and by no one more strenuously than myself I am now satisfied that... your theory is better adapted than any former one, for explaining the relation of mixed gases to each other, and especially the connection between gases and water." '■ This support must have been specially gratifying to Dalton, in view of the keen opposition and criticism which the theory was receiving in other quarters. It probably confirmed and enhanced the "almost life-long friendship " between the two men, which is referred to repeatedly in this series of papers. The ''' mixed gases'' controversy. The controversy which was aroused by Dalton's theory of mixed gases affords proof at once of the interest taken in his mechanical explanation of the phenomenon, and of the tenacity with which the chemical explanation was adhered to. The view that air is a chemical compound was maintained with a persistency which is hardly credible now, and which throws into relief the originality and vigour of mind which Dalton showed in forming and urging a wiser view. The balance of opinion was against him, for his opponents included Claude Louis Berthollet, Thomas Thomson, John Gough, John Murray, and Humphry Davy. Dalton's contention, that the diffusion of gases is a physical phenomenon, was at length fully and finally recognised in the Kinetic Theory of Gases. Meantime Dalton had to do his best in the circumstances, and the ^- NicholsoiC s Journ., [2], vol. 8, p. 297, 1S04. 8 Meldrum, Developwcut of the Atomic Theory. particular mechanism by which he accounted for diffusion proved specially vulnerable/" The most eager critic of the mechanical explanation was Gough. He wrote numerous letters and essays against it, which were answered by Dalton, and on one occasion by Henry. One of his criticisms was acute. If, as Dalton supposed, the particles of oxygen in the atmosphere have no action on the particles of nitrogen, and vice versa, this must affect the transmission of sound. Gough said the oxygen must transmit one sound wave and the nitrogen another, each with its own velocity, so that at a sufficient distance a sound should be heard double. Berthollet, in his " Essai de Chimie Statique," shows himself a whole-hearted believer in the chemical theory. " It appears to me incontrovertible, that it is a true chemical action which produces the solution of liquids in gases, and evaporation."" He was unfavourably im- pressed by the diagram appended to the " Mixed Gases " Essay, in which Dalton exhibits particles of oxygen, nitrogen, water and carbon dioxide existing in the atmosphere independently of one another. ^^ " A diagram in which Dalton has attempted to show how different gaseous molecules may be disposed in the same space, is... only a figment of the imagination."^" Thomas Thomson's interest was roused to a high pitch by Dalton's theory. Whilst expressly withholding his assent to it, he noticed it in edition after edition of 1" As a matter of fact, Dalton did for years believe that " portions of gas of different kinds behave to each other in a different manner from portions of gas of the same kind . . . whereas there is no difference between the two cases." Clerk Maxwell, " Theory of Heat,"' loth ed., pp. 28-29. 1* Op. cit., § 164. ^^ Manchester Memoirs, [i], vol. S, p. 602, 1802. i« Op. «Y.,§244. Manchester Memoirs, Vol. Iv. ( 1 9 1 1 ), No. 5- 9 his " System of Chemistry." Dalton's reply to the criticism in the second edition had a notable consequence. Thomson visited Manchester in order to get an explana- tion of the theory from the author himself, and it was on this occasion that Dalton told him about the chemical atomic theory. II. The beginning and course of Dalton's EXPERIMENTAL WORK. The Beginning. Dalton did not begin original experimental work till 1799, when he was thirty-three years of age, and had been six years in Manchester. Up to then he had confined himself to work of observation, chiefly in meteor- ology. The first paper in which his own experiments occupy a considerable space is his memoir on the power of fluids to conduct heat. It was read before this Society on the 12th April, 1799. A previous paper of his, read six weeks earlier, is of quite another stamp. The title of this is as follows : — " A paper, containing Experiments and Observations to determine whether the quantity of Rain and Dew is equal to the quantity of water carried off by the rivers and raised by Evaporation ; with an inquiry into the origin of springs." Now, not only are the experiments recorded in this paper hardly worthy of the name, but the subject itself is of the nature of a forlorn hope. Dalton could not have embarked on such a hopeless inquiry as this, if he had been accustomed to experimental research, and had experi- enced the advantages to be gained simply by limiting the scope of an investigation. This paper, therefore, marks the end of the first stage in his scientific career. By April of the year 1799 he was in the full swing of experimental work. lO Meldrum, Development of the Atomic Theory. Experiments connected with the vapour pressure of water. A paper which Dalton read April i8th, 1800, marks another stage on the way. The title, which is significant of much, runs as follows : — " Experimental Essays, to determine the Expansion of Gases by Heat, and the maximnm of steam or aqueous vapour, which any gas of a given temperature can admit of ; with observations on the common or improved Steam Engines." On this title four remarks may be made, (i) Dalton had arrived by April, 1800, at the idea, which forms the central fundamental conception of the second and third of the "Experimental Essays" of October, 1801, of the vapour pressure of water. He had begun to con- sider other gases besides the air, and knew that the maximum of water vapour in any gas is independent of the nature of the gas. It was in order to show this at different temperatures that he began to measure the " expansion of gases by heat." (2) There is a practical connection between the expan- sion of gases by heat, and the original topic of the water vapour in the atmosphere. Dalton's explanation of the ■discrepancies betv/een the results of earlier workers on the subject is that it " arose from the want of due care to keep the apparatus and materials free from moisture." ^'^ (3) This paper, although passed for publication by the Society, never appeared. Nothing remains of the " Obser- vations on the common or improved Steam Engines." (4) Perhaps Dalton had discovered by April, 1800, what we know as Charles' law, that different gases have the same expansion by heat. But he does not make this claim himself. The law forms the subject of the fourth of the " Experimental Essays," and this fourth essay, ^' Manchester Memoirs, [i], vol. 5, p. 596, 1802. Mauckesier ATonoirs, Vol. Iv. (191 1), No. 5. 11 though usually dated October, 1801, was, as a matter of fact, not read then as the first three were before this Society. Later developments. Between the paper of April, 1800, and the " Experi- mental Essays" of October, 1801, Dalton took up the study of only two additional topics. One of these, the vapour pressure of other liquids than water, was a natural outcome of previous work, and calls for no special com- ment here. The other was that of the explanation of the phenomena of mixed gases. This, a large topic and not an experimental one, is discussed in the last section of this paper. But here is the place to point out that Dalton's reflections on this subject led to two experi- mental inquiries of the greatest consequence. One of these, already mentioned in this paper, was the study of the diffusion of gases. The other was the determination by Dalton of the composition of the atmosphere, the outcome of which, as will be shown in the next paper, was the formation of the chemical theory. III. The two forms of the physical theory AND the dates OF THEH^ ORIGIN. The date of the first diffusion hypothesis. Dalton, in the Introduction to his set of four "Experi- mental Essays" of October, 1801, explains that this theory of mixed gases was arrived at after his other results. " The first law \_i.e., the mixed gases theory] which is as a mirror in which all the experiments are best viewed, was last detected, and after all the particular facts had been previously ascertained." ^^ ^* Manthcstcr Memoirs, [i], vol. 5, p. 536. 12 Meldrum, Dcvclopmen t of the A torn ic T/ieorj '. There is no reason to question this statement. It is true that Dalton's historical narratives, as has been shown in the second paper of this series, cannot be accepted at their face value. But this is a contemporary statement, and, as such, must receive a considerable degree of credit. The physical theory was formed between April, 1800, and September of the following year. There is no hint of it in the title of the paper '.vhich Dalton read on the 1 8th April of the earlier year. Again, the date of the first sketch of the theory, which he sent to NicJiolson's Jotirnal, is the 14th September, 1801, and the theory can hardly have arisen earlier than August. It is true that Angus Smith assigns the reading of the essay " On the Constitution of Mixed Gases" to July 31st, and October 2nd and i6th for the reading of the 2nd and 3rd essays respectively.'^ But the dates mentioned at the head of the papers in the MancJiester Memoirs, are the 2nd, i6th, and 30th October. Dalton must have known the dates on which his own papers were read, and as the author he was interested in not dating them later than was neces- sary. In the Minute-book of the Society the title of each of these papers was entered on a left hand page, and the date and other particulars of the meeting at which the paper was read on the right hand page. Angus Smith has made the slip, which one can easily understand, of assigning the reading of a paper to the meeting minuted on the previous page. The influence of Neivton on Dalton. The theory was formed under a new influence. Between April, 1800, and August or September, 1801 ^" Angus Smith, "Memoir of Dalton," p. 254. These are not the only wrong dates in his list of Dalton's papers. Manchester AIe})wirs, Vol. Iv. ( 1 9 1 1 ), No. 5. 1 3. Dalton came under the stimulus of Newton's atomic theory. Everything goes to show that this had a great effect on him. He hardly mentions Newton in his early writings. In 1801, and subsequently, he quoted Newton on every suitable occasion, and in particular he mentions the 23rd Proposition of the 2nd Book of the " i'rincipia " at least five times. The mutually repulsive particles of this proposition play their part in Dalton's theory. The wording of it shows this : — " When two elastic fluids, denoted by A and B are mixed together^ there is no mutual repulsion amongst their particles ;, that is the particles of A do not repel those of B, as they do one another." ^° Dalton's theory is a true development of the theory of Newton, in respect that it is a static one, representing the atoms as being, ultimately, at rest among themselves. If, as was shown in the 3rd paper of this series, Newton, in forming his theory deliberately set aside the dynamic ideas of Descartes, it is to be remembered that these ideas at length found expression in the Kinetic Theory of Gases. The amended diffusion hypotliesis. As already stated in the second paper of this series, Dalton explained in a lecture which he gave in 18 10, that he had not at first contemplated the effect o{ difference of size in the particles of elastic fluids. But he reflected that if the sizes be different, then on the supposition that the repulsive power is heat, no equilibrium can be established by particles of different sizes pressing against each other." On consideration, he found "that the sizes must be different ; " " thus," he concludes, " we arrive at the reason for that diffusion of every gas through every other gas, -" Manchcsier i]Ieiiioirs, [l], vol. 5, p. 536, l8o2. 14 Meldrum, DevclopDient of the Atomic Theory. without calling in any other repulsive power than the well known one oi heat" This, he says, occurred in 1805.°^ In later life, Dalton gave up this amended hypothesis, and reverted to his original one.™ But in 1808 he ex- pounded them both in the " New System." This may seem inconsistent of him, inasmuch as the two hypotheses are different from one another. Yet they are both forms of the physical atomic theory. Dalton's consistency lies in his adherence to a mechanical hypothesis in contrast to a chemical one. The question of the precise mechanism was subsidiary, and the mixed gases controversy turned entirely on the theory which Dalton advanced in 1801. No one took any notice of his change of front. It has, therefore, not been necessary to consider the amended diffusion hypothesis till now. The hypothesis is less important for its own sake than in its bearing, or supposed bearing, on the development of Dalton's chemical theory. The amended hypothesis and the chemical atomic theory. In the lecture already quoted, Dalton connects this amended hypothesis with the genesis of his chemical atomic theory. " The different sizes of the particles of elastic fluids under like circumstances .... being once established, it became an object to determine the relative sizes and lueigJits together with the relative nnmber of atoms in a given volume. This led the way to the combination of gases .... Thus a train of investigations was laid for determining the nnmber and zveight of all chemical elementary principles which enter into any sort of combination with one another." -' -' Roscoe and Harden, " New view of the origin of Dalton's Atomic Theory," pp. 16-17. -- Phil. Trans., 1826, part 2, p. 174. -" Roscoe and Harden, loc. cil. Miuic/iesier Meviohs, Vol. Iv. (191 1), No. 5- 15 " This led the way to the combination of gases." Undoubtedly the combination of gases was the basis of Dalton's chemical theory, and the gist of his narrative is, that YiQ first concluded the particles of different gases to be different in size, and subscquoitly arrived at his chemical theory. iSoj or iSoj ? Roscoe and Harden, instead of taking this narrative as a document requiring interpretation in the light of the available information, and above all, in the light of Dalton's habit of mind, have accepted it at its face value. Even then they are compelled to admit there is something wrong. The note-books shew that the chemical theory was formed in 1803, and if the amended diffusion hypo- thesis was formed previously, then the date, 1805, which Dalton gives, must be wrong. Roscoe and Harden con- clude that the date of the amended hypothesis is 1803.-* The date is iSo^, There are two grave objections to the supposition that the theories were formed in the order given by Dalton. One of these is based on the nature of the theories, and will be considered in the next paper. The other has to do with the genesis of the diffusion hypothesis. Roscoe and Harden have failed to quote from the note-book the passage which deals with this. It is as follows : — " On the iiltimate atoms of elastic fluids. "There are but three positions that are any way likely to be true on this head. " I. The ult. atoms of all gases are of the same weight. 2* op. cil,, p. 25. l6 yiKLD'RXl'M, Deve/opjnent of the A to)inc TJicory. " 2. The ult. atoms are of the same relative weight as the gases themselves. " 3. That neither of these positions is accurate. " According to the first the gases of greatest specific gravity are those whose particles are closest and the diameters of the elastic particles will be as the cube root of the sp. gr. This cannot be true for nit. gas which is made up of azot and oxygen is lighter than oxygen itself ; and so is aq. vapour than oxygen one of its •constituents." ^^ " According to the 2nd position all gases will have the same number of particles, and consequently the same distances of each in a given volume, under like circum- stances. This position is contradicted by facts : for all ■compounds would be heavier than their simples upon this principle, which is contrary to experience. " The two former positions being disproved, it follows that when two gases of like force, &c., are presented to each other, the number of particles in a given surface of one of them will not be the same as in the other ; conse- quently, no proper equilibrium can take place." -" This material is as important as anything on the subject can well be. The pages quoted, Nos. 109 and III of the note-book, amount to a summary of Dalton's reasoning on the subject of the sizes of atoms, leading to his decision in favour of the new diffusion hypothesis. It is easy to assign a date to this decision. By reason of the subject-matter, pages 107, 109, and iii are closely con- nected with one another. Page 107 contains a table of the weights and diameters of atoms, a table which, it may well be supposed, was drawn up in order to illustrate X)alton's inquiry into the sizes of atoms. It is dated -^ Note-books, vol. i, p. 109. '^' Op. cit., p. III. Manchester Mevioirs, Vol. h. {\gi i), No. 5. 17 September 14th, 1804, and this is the approximate date of the amended diffusion theory. Dalton probably influenced by Thomson and Gotigh. Up to this time Dalton had given no sign of anything but the fullest confidence in his original theory. He had defended it eagerly, and, as late as June, had been encouraged in his belief by the accession of William Henry to his side. What then could have induced Dalton, not a very impressionable man, to reconsider the matter ? It may be assumed, in the absence of any positive information on the subject, that the change was due partly to Thomas Thomson and partly to John Gough. As has already been mentioned more than once in these papers, Thomson visited Manchester with the express object of discussing the mixed gases theory with Dalton. Now everything goes to show that Thomson made a considerable impression on him and won his confidence. He explained the chemical theory to Thomson in detail, and afterwards mentioned Thomson's opinions regarding mixed gases, although adverse to his own, with the utmost respect.-^ Consequently one can well believe that Thomson's scepticism regarding the original mixed gases theory began to shake his confidence in it. Again, John Gough had written two letters, which appeared in Nicholson's Journal^ criticising the theory. The criticism was effective, for Dalton, although he continued to main- tain his theory, made no answer at the time to Gough's argument regarding the velocity of sound. Gough's letters are dated July i6th and August 23rd, 1804, respectively. The interview between Dalton and Thomson occurred on ■-" "New System of Chemical Philosophy," 1808, p. 72. 1 8 Meldrum, Development of the Atomic Theory. the 27th August, and Dalton's reply to Gough is dated 8th September. Thus Thomson's objections to the theory, with Gough's in addition, may have compelled Dalton to reconsider the matter. There was time for reconsideration between the 8th September and the 14th, the date of Dalton's decision to put the explanation of the diffusion of gases on a new basis. The principal references connected ivitJi the theory of mixed gases, 1792. 1. "On Evaporation," by Jean Andre Deluc. Phil. Trans.,. p. 400. 1793- 2. " jMeteorological Observations and Essays," by John Dalton. 1799. 3. " Experiments and Observations, to determine whether the quantity of Rain and Dew is equal to the quantity of Water carried off by the rivers and raised by evaporation ; with an Inquiry into the Origin of Springs," by John Dalton. Read* March ist. Vwh. Manchester AlemoirSy vol. 5, part 2, p. 346, 1802. (The footnote, p. 351, was added after the paper was read.) 1800. 4. " Experimental Essays, to determine the Expansion of Gases by Heat, and the maximum of Steam or Aqueous Vapour, which any Gas of a given temperature can admit of; with observations on the common and improved Steam Engines," by John Dalton. Read April i8th. Never published in full ; see no. 8. * In ihe above list, " read '" means read before the Manchester Literary and Philosophical Society. Manchester Memoirs, Vol. Iv. (191 1), No. 5. 19 1801. 5. " New theory of the constitution of mixed aeriform fluids, and particularly of the atmosphere," by John Dalton. Written September 14th. Pub. Nicholson' s Jour., [i], vol. 5, p. 241. 6-g. " Experimental Essays on the Constitution of mixed gases ; on the force of steam or vapour from water and other liquids in different temperatures, both in a torricellian vacuum and in air ; on evaporation ; and on the expansion of gases by heat," by John Dalton. The ist of these four essays was read Oct. 2nd, the 2nd Oct. i6th, the 3rd Oct. 30th. Pub. Manchester Memoirs, [r], vol. 5, p. 535, 1802. 1802. 10. "System of Chemistry," by Thomas Thomson, ist ed., vol. 3, p. 270. 11. "New theory of the constitution of mixed gases eluci- dated," by John Dalton. Written Nov. 18th. Pub. Nicholsoiis Jour., [2 J, vol. 3, p. 267. (Chiefly called forth by no. 10.) 12. "Experimental Inquiry into the Proportion of the several gases or elastic fluids constituting the atmosphere," by John Dalton. Read Nov. 12th. Pub. Manchester Memoirs, [2], vol. i, p. 244, 1805. 1803. 13. "EssaideChimieStatique,"byC. L. Berthollet (especially §§ 158, 160, 163, 164, 171, 240, 242—244). 14. "On the tendency of elastic fluids to diffusion through each other," by John Dalton. Read Jan. 28th. Pub. Manchester Memoirs, [2], vol. i, p. 259, 1805. 15. "On the absorption of gases by water and other liquids," by John Dalton. Read Oct. 21st. Pub. Manchester Memoirs, [2], vol. i, p. 271, 1805. 20 Meldrum, Developmetit of the Atomic Theory. 1 6. "An Essay on the theory of mixed gases and the state of water in the atmosphere," by John Gough. Read Nov. 4th. Pub. Manchester Memoirs, [2], vol. i, p. 296, 1805. 17. "A reply to Mr. Dalton's objections to a late theory of mixed gases," by John Gough. Written Dec. 2nd. Read Jan. 27th, 1804. Pub. Manchester Memoirs, [2], vol. I, p. 405, 1805. i8. "Appendix to Mr. William Henry's paper, on the quantity of gases absorbed by water, at different temperatures, and under different pressures." Phil. Trans., p. 274. 1804. 19. "System of Chemistry," by Thomas Thomson, 2nd ed., vol. 3, p. 316. 20. "On the supposed chemical affinity of the elements of common air; with remarks on Dr. Thomson's observa- tions on that subject," by John Dalton. Written June 1 6th. Pub. Nicholson's Jour., [2], vol. 8, p. 145. (A reply chiefly to no. 19.) 21. "Illustration of Mr. Dalton's theory of the constitution of mixed gases," in a letter from Mr. Wm. Henry, of Man- chester, to Mr. Dalton. Written June 20th, read June 29th. Pub. Nicholson's Joicr., [2], vol. 8, p. 297. 22. "On the solution of water in the atmosphere, and on the nature of atmospherical air," by John Gough. Written July 1 6th. Pub. Nicholson' s Jour., [2], vol. 8, p. 243. 23. " Strictures on Mr. Dalton's doctrine of mixed gases, and an answer to Mr. Henry's defence of the same," by John Gough. Written Aug. 23rd. Pub. Nicholson' s Jour., [2], vol. 9, p. 52. (A reply to nos. 20 and 21.) 24. " Observations on Mr. Gough's strictures on the doctrines of mixed gases, &c.," by John Dalton. Written Sept. 8th. Pub. Nicholson's Jour., [2], vol. 9, p. 89. (A reply to nos. 22 and 23.) Manchester Memoirs, Vol. Iv. (191 1), No. 5. 21 25. "Atmospherical air not a mechanical mixture of the oxigenous and azotic gases, demonstrated from the specific gravities of these fluids," by John Gough. ^Vrilten Sept. 5th. Pub. Nicho/sofi's Jour., [2], vol. 9, p. 107. 26. Letter to the Editor from Mr. William Henry in reply to Mr. Gough. Written Sept. 13th. Pub. Nicholson^ s Jour., [2], vol. 9, p. 126. (In reply to nos. 22 and 23.) 27. " Reply to Mr. Dalton on the constitution of mixed gases," by John Gough. Written Oct. i6th. Pub. Nicholsoiis Jour., [2J, vol. 9, p. 160. (A reply to no. 24.) 28. "Observations on Mr. Gough's two letters on ujixed gases," by John Dalton. Written Nov. 15th. Pub. Nicholson^ s Jour., [2], vol. 9, p. 269 (in reply to nos. 25 and 27). 29. " Further observations on the constitution of mixed gases," by John Gough. Written Dec. 13th. Pub. Nicholson's Jour., [2], vol. 10, p. 20, 1805. 1805. 30. " Remarks on Mr. Gough's two Essays on Mixed Gases, and on Professor Schmidt's experiments on the expan- sion of dry and moist air by heat," by John Dalton. Read Oct. 4th. Pub. Manchester Memoirs, [2], vol. r, p. 425 (a reply to nos. 16 and 17). 1806. 31. "System of Chemistry," by John Murray. Vol. 2, pp. 48- 53, and note E. 1807. 32. "System of Chemistry," by Thomas Thomson. 3rd ed., vol. 3, p. 440. 33. "On the Chemical composition of the Atmosphere." Works, vol. 8, pp. 252-255, by Humphry Davy. 22 Meldrum, Development of the Atoiiiic Theory. 1808. 34. "New System of Chemical Philosophy," by John Dalton, pp. 150-208. 1809. 35. " Experiments on the expansion of moist air raised to a boiling temperature," by John Gough. Written May 22nd. Pub. Nicholsoiis Jour.., [2], vol. 23, p 182. 36. " Sur le melange reciprcque des gaz," par C. L. Berthollet. Mem. cfArceiiit, vol. 2, p. 463 (a repetition of Dalton's experiments in no. 14). 1826. 37. " On the constitution of the Atmosphere," by John Dalton. Fhil. Irans., part 2, p. 174. 1837- 38. " Sequel to an Essay on the constitution of the Atmosphere," by John Dalton. Phil. Trans., p. 347. 1834. 39. Dr. Prout's reply to Dr. W. Charles Henry. Written July iSth. Phil. Mag., [3], vol 5, p. 133. 1844. 40. " Observations on the Diffusion of Gases," by T. S. Thomson. Phil Mag., [3], vol. 25, p. 51. 1842. 41. "Elements of Chemistry," by Thomas Graham, pp. 69, 70. 71, 75- Manchester Memoirs, Vol. Iv. (191 0. ^^0. 0. VI. The Development of the Atomic Theory : (5) Dalton's Chemical Theory. By Andrew Nor^ian Meldrum, D.Sc. ( Carnegie A'esearr/i Fclloiv. ) (Commiiiikated by Prof. H. B. Dixon, M.A., F.R.S.) Received October, igio. Read January 2^th. igi i. Introduction. In the year 1801 Dalton's physical atomic theory (described in the fourth paper of this series) was devised as an explanation of the diffusion of gases. Since the pre- vailing tendency of the time had been to regard diffusion as due to chemical affinity between the gases concerned, Dalton was forced to consider carefully the nature of physical and chemical changes, and to draw a distinction between them. His own theory of diffusion turned on this distinction. Thus, in the course of his argument against the supposition that diffusion is due to chemical affinity, he asks the question, " Why do not oxygenous and azotic gases, taken in due proportion and mixed, constitute nitric acid gas, another elastic fluid, totally distinct in its properties, from either of the ingredients."^ Obviously, therefore, whilst Dalton's attention was being d\rec\.&d principally to physical phenomena, he had in his mind a distinct conception of chemical change. The object of this paper is to consider how Dalton passed from the physical atomic theory, which was formed first, to the chemical one, which was formed afterwards. The author has already shown, in the second paper of this series, that the various narratives we possess of the origin of the chemical theory, can be traced back to ^ Manchester Memoirs, vol. 5, pp. 538-539, 1802. March ytli, igii. Meldrum, Developmoit of tJic Atomic Theory, Dalton himself. This is simply what was to be expected in the nature of the case. Moreover, since Dalton was inconsistent in the matter, no single account of his can be accepted at its face value. The version of the origin which is advanced in this paper, consequently, need not be rejected off-hand, as not having received the sanction of Dalton. It is offered as a fair account of the present state of our knowledge, on a matter on which absolute certainty is not yet attainable. The paper is divided into two parts : — I. The princi- ples of Dalton's theory ; II. The genesis of the theory. I. The principles of Dalton's theory. Hie first table of atomic weights. For the present purpose of studying the origin of the chemical theory, Dalton's note-books contain material of inestimable value : they afford facts which cannot be disputed. Under date 6th September, 1S03, there is an atomic weight table of the highest interest. It is quoted by Roscoe and Harden as follows : — * Ult. at. hydrogen ... ... i » » oxygen 566 „ » azote 4 „ „ carbon 4-5 „ „ water ... ... 6 66 „ „ ammonia ... ... 5 „ „ nitrous gas... ... 966 „ „ „ oxide ... 1366 „ „ nitric acid ... ... 1 5'32 „ „ sulphur ... ... 17 „ „ sulphurous acid ... 2266 „ „ sulphuric „ ... 2832 „ „ carbonic „ ... 158 ,, „ oxide of carbon ... 102 * " New View of the Origin of Dalton's Atomic Theory," p. 28. . Manchester Memoirs, Vol. Iv. (191 1), No. 45. 3 This table of atomic weights is of extraordinary interest because, besides being the earliest known, it is based on the same ideas as the one published in the " New System '' five years later. There is only one change : sulphurous and sulphuric acids in the earlier table are virtually SO and SOj respectively, and in the later table they are SO. and SO.,. But this does not affect the fact that after the table was drawn up in 1803, Dalton made no essential change in the theory. The principles of 1S03 remain as nearly as possible unchanged in 1808, so far as one can judge of principles by results. In the one scheme just as in the other, the compound atom of water consists of I atom of hydrogen and i of oxygen, that of ammonia of i of hydrogen and i of nitrogen. Nitrous gas is virtually NO, nitric acid is NO., nitrous oxide N.O, carbonic oxide is CO, carbonic acid is CO2. Debus on the '' Dalton- Avogadro " hypothesis. Debus has devoted a series of papers to the study of the principles on which Dalton arrived at chemical formulae and atomic weights. The whole series may be said to depend on the assumption that Dalton deliberately made a mystery of the evolution of his theory. " Der geniale Baumeister hat sorgfaltig alle Werkzeuge und Plane entfernt und zeigt ohne einleitende Bemerkungen sofort das fertige Gebaude." - This is the kind of state- ment which ought not to be made except as the result of an exhaustive study of the available material. Everyone must admit that the subject is obscure, but, as will appear in the course of this paper, there is little justification for saying that Dalton deliberately (sorgfaltig) made it so. The true explanation of the obscurity is that the task of - Zeitsch. pliysik. Chan., 1899, vol. 29, p. 266. 4 Meldkum, Development of t lie Atomic Theory. considering how his own ideas had arisen was uncongenial to him, and he never devoted his mind to it. As the result of his studies, Debus conckided that Dalton was greatly influenced, during the development of his atomic theory, by the supposition that the particles of different gases under similar conditions are of the same size. This doctrine, which is usually known as Avog- adro's hypothesis, Debus calls the " Dalton -Avogadro" hypothesis. Debus first advanced this belief of his in a pamphlet entitled, " Ueber einige Fundamentalsatze der Chemie, insbesondere das Dalton-Avogadrosche Gesetz " (1894, Cassel). His opinion having been controverted by Roscoe and Harden, in their " New View of the Origin of Dalton's Atomic Theory," he replied, and a controversy ensued, in which G. W. A. Kahlbaum also took part. The series of papers is as follows : — Debus, Zeitsch. physikal. Cliem., vol. 20, p. 359, 1896 (or PJiil. Mag., vol. 42, p. 350, 1896); Roscoe and Harden, Zeitsch. physikal. Chem., vol. 22, p. 241, 1897 (or Phil. Mag., vol. 43, p. 153, 1897); Debus, Zeitsch. physikal. Chem..,. vol. 24, p. 325, 1897; vol. 29, p. 266, 1899; Kahlbaum, Zeitsch. physikal. Chem., vol. 29, p. 700, 1899; Debus, Zeitsch. physikal Chem., vol. 30, p. 556, 1899. Debus can justify his belief in two ways : — (i) Dalton certainly stated in 1808 that he once had a sort of belief in the hypothesis in question. " At the time I formed the theory of mixed gases, I had a confused idea, as many have, I suppose at this time, that the particles of elastic fluids are all of the same size ; that a given volume of oxygenous gas contains just as many particles as the same volume of hydrogenous ; or if not, that we have no. data from which the question could be solved. But .... Manchester Mcuioirs, Vol. h. (191 1), No. 0. 5 I became convinced that different gases have not their particles of the same size." ' (2) Debus argues, from a phrase in Thomas Thomson's first sketch of the atomic theory, that Dalton was still in 1804 a believer in the hypothesis. This is the phrase, ^' the density of the atoms." The ''density of the atoms'^ The interpretation of this phrase is open to questionj and Roscoe and Harden do not agree with Debus on the matter. But neither they nor any of the parties to the controversy seem to be aware that Dalton put exactly the same construction on the phrase as Debus, and at the same time repudiated the opinion which it attributed to him. " It is rather amusing to me to observe the different manners in which a cursory view of the atomic system strikes different observers. Dr. Thomson . . , used the phrase density of the atoms indifferently for iveight of the nionis, thereby implying that all atoms are of the same size, and differ only in density ; but he has since very properly discontinued the use of the phrase."^ It is, of course, impossible that a statement, made by Dalton in 18 14, can be taken to prove that he did not use a misleading expression in a conversation held ten years earlier. He may have used the phrase in question in his interview with Thomson, or Thomson may have originated the phrase. These are the two possibilities. But the matter is not one of high importance. There are far stronger arguments than this statement of the year 1 8 14 can be, against the opinion held by Debus. " "New System of Chemical I'hilo.soijhy," iSoS, pp. 187-1S8. * Ann. of Phil., vol. 3, p. 175, 1814. 6 MeldrUM, Development of tJic Atomic TJicory. Dalton practically ignores the hypothesis. The really important question is, the sense in which Dalton held this hypothesis. Did he perceive and con- sider all its consequences, immediate and remote, and did he, in any \va\', act upon his belief in it ? That he did none of these things is the plain meaning of the passage in which he speaks of his holding the hypothesis as a "confused idea." There are four different ways in which Dalton might have applied the hypothesis, or drawn deductions from it : 1. The hypothesis is to the effect that particles of nitrogen and ox\-gen are of the same size. Dalton's first explanation of diffusion was that particles of oxygen neither attract nor repel those of nitrogen. Between these two opinions there is no necessary connection. He did not hold the diffusion theory as a logical consequence of the hypothesis, and he did not even specify the hypo- thesis in his explanation of the theory. 2. Dalton did not use the hypothesis as a means of arriving at atomic weights and formula;. He used for that purpose the i : i rule, which led him to the formula OH for water, whilst the hypothesis must have led to the formula H.^O. Thomson, in his first sketch of the theory, says expressly that the i : i rule was " the hypothesis on which the whole of Mr. Dalton's notions ... is founded."^ 3. What is known as Gay-Lussac's law, regarding the combining volumes of gases, is a necessary con- sequence of the hypothesis. This everyone must admit. Yet Dalton did not at once deduce the law from the hypothesis, and when at length he did so, and endeavoured to test it experimentally, he regarded his results as dis- '' " S}'stem of Chemistry,'' 31x1 edition, 1S07, vol. 3, p. 424. AlcuicJicster hfenioirs, J^o/. h: (igii), No. ^. 7 province both doctrines. Debus, as the author has pointed out elsewhere, has committed himself to the opinion that Dalton could be at one and the same time a believer in the hypothesis and not in the law.'' 4. Finally, Dalton held this hypothesis without con- sidering that it leads to the conclusion, familiar now to chemists, that the " atoms " of hydrogen, oxygen and other elements are divisible. There is no evidence, not the faintest indication, that Dalton had realised the hypothesis before the end of the year 1803, ^^ ^^W o"g of these four ways. It is, therefore, impossible to suppose that the hypothesis — the "confused idea" — had any influence on him whilst he was forming his chemical atomic theory, T/ie main principles of Daltuiis system. The principles on which Dalton based his theory must have continued the same from 1803 to 1808, simply because his opinions regarding the " atom " of water, of ammonia, etc., remained the same. The general prin- ciples regarding the combination of atoms, which he set out in 1808, are somewhat cumbrous, and some of them superfluous. They can be reduced to two: — (i) That atoms of different kinds tend to combine in the propor- tion I : I rather than in any other, that the next propor- tion to occur is I : 2, then i : 3, and so on ; (2) that when two compounds of the same two elements are gaseous, the lighter is binary and the heavier tertiary. It is true that this second principle is not to be found among the set of rules which Dalton gives in the " New System of Chemical Philosophy." He says there that « " Avogadro and Dalton — the standing in Chemistry of their hypotheses," 1904, pp. 63-66. 8 Meldrum, Deuclopuient of the Atomic Tlieoty. "a binary compound should always be specifically heavier than the mere mixture of its two ingredients " [compounds and ingredients being supposed to be gaseous]. This rule is open to two objections : — (i) It is not true, as the case of hydrochloric acid shows ; (2) it is of no use and was not used for the problem that Dalton had to solve. It cannot be used to ascertain whether the two gaseous oxides of carbon ought to receive the formula CO and CO2 respectively, or CoO and CO. In the 2nd part of the " New System " he says : — " carbonic acid is of greater specific gravity than carbonic oxide, and on that account it may be presumed to be the ternary or more complex element \^sic\. It must, however, be allowed that this circumstance is rather an indication than a proof of the fact." ' One can well believe that it was on this principle Dalton arrived at the molecular constitution of these gases, and of nitric and nitrous oxides as well, in the year 1803. The connection between the physical and the chemical theories. The first rule has been called the rule of " greatest simplicity," not only in allusion to its character, but as meaning that it is based on the instinct for simplicity and needs no other justification. As a matter of fact Dalton deduced it from first principles. Dr. Bostock, in the course of a criticism of the atomic theory, raised the question, " When bodies unite only in one proportion, whence do we learn that the combination must be binary?" In answer Dalton gave an explanation, which shows that Newton's postulate of similar particles, which are *' mutually repulsive," was the fundamental idea of the "^ "New System ofCliemical Philosophy,"' iSiO, p. 369. Manchester HTcvioirs, Vo/. h. (191 1), No, 4>. 9 chemical as it had been of the physical atomic theory. ^' When an element A has an affinity for another B, I see no mechanical reason why it should not take as many atoms of B as are presented to it, and can possibly come into contact with it, . . . except in so far as the repulsion of the atoms of B among themselves are \sic\ more than a match for the attraction of an atom of A. Now this repulsion begins with 2 atoms of B to i of A, in which case the 2 atoms of B are diametrically opposed ; it increases with 3 atoms of B to i of A, in which case the atoms of B are only 120° asunder .... and so on in proportion to the number of atoms. It is evident then from these positions, that, as far as powers of attraction and repulsion are concerned (and we know of no other in chemistry) . . . binary compounds must first be formed in the ordinary course of things, then ternary and so on, till the repulsion of the atoms of B . . . refuse to admit any more."" Consequently, Newton's postulate of similar particles which are mutually repulsive, is the basis of both the physical and the chemical atomic theories of Dalton. II. The genesis of the ciie^mical theory. The inductive and deductive accounts of the genesis. This discussion of principles, however, does not exhaust the subject. Much remains obscure regarding the train of thought which Dalton followed in passing from the physical to the chemical theory. The crucial question is, how he arrived at, what suggested, the doctrine of combination of atoms in multiple proportion? Two main accounts of the origin of the theory have '^ Nicholson'' s Join ., vol. 29, p. 147, iSii ; see also '' New System of Chemical Philosophy," vol. i, p. 216, iSoS. lo Mkldrum, DevelopJiient of the Atomic Theory. been offered. They have already been mentioned in the second paper of this series. The first of these, coming direct from Thomas Thomson, is that Dalton discovered the composition of marsh gas and olefiant gas and was led thereupon to perceive the law of multiple proportions, and to devise his chemical theory as an explanation of the law. This may be called the inductive account. Again, Roscoe and Harden accept an account, offered by Dalton, which may be called the deductive one. Dalton had formed his diffusion hypothesis without considering the " effect of difference of size in the particles of elastic fluids." On consideration he found that " the sizes must be different," and thereupon he revised his diffusion theory. He then introduces the subject of the chemical theory : — " The different si::es of the particles of elastic fluids .... being once established, it became an object to determine the relative si.zes and weights, together with the relative number of atoms in a given volume. This led the way to the combination of gases," etc. Objections to the purely inductive and ded^ictive accounts. There being these two accounts, the inductive one and the deductive, of the origin of the theory, there arises the question, which comes nearer the truth? The Board of Education has recently committed itself to an opinion on this topic, in the course of its criticisms on the answers of students to its questions on chemistry. The particular question was : — " Give a short account of Dalton's atomic theory, and discuss its value in explaining the laws of chemical combination." Teachers of chemistry, to judge from the reference made to them, have been adopting Roscoe and MancJiester Memoirs, Vol. Iv. (191 1), No. <>. ir Harden's view of the matter. "... The teachers are to blame ... in allowing so many of their students to put the " cart before the horse" as they do in connection with the atomic theory. The idea seems to prevail that the laws of chemical combination follow from the atomic theory, whereas the laws of combination were established first as the results of experiments, and the atomic theory of Dalton provides an explanation of the facts."" It is, of course, begging the question to assume that the matter is as simple as this. Everyone knows which is the cart and which is the horse, and no one knows for certain how Dalton's chemical theory arose. Again, one may urge, that supposing the origin of the theory to be a controversial matter, the Board of Education is not called upon to take one side or the other, and indeed,, might well avoid such topics in its examination papers. The matter, however, is no longer controversial, being so far settled that the purely inductive view of the origin is quite untenable. There is the objection to it in prin- ciple, that it says nothing about Dalton's physical theory to which W. C. Henry drew attention long ago, and Roscoe and Harden recently. Besides, Roscoe and Harden have advanced objections to it in detail, which must be final to anyone who considers them.^" Reasons must now be offered for rejecting the deductive account which Roscoe and Harden have accepted. The gist of it is that Ualton fi^st satisfied himself that the atoms of different gases have different sizes, and then devised the chemical theor}\ This, Dalton's own narrative, has already been quoted on p. 10. He gave it seven years after the events which it relates, and it is quite unsatisfactory. It does not condescend to " " Science Examinations," 1909, p. 119. Board of Education. ^ " " New View of the Origin of Dalton's Atomic Theory,"' p. 2S. 12 MeldrUM, DevelopDient of the Atomic Theory. particulars and instances, Dalton does not explain, nor is it obvious that anyone can explain, how he was to test the sizes of atoms without some kind of chemical theory. One may either assume that different atoms have the same size, and act accordingly, or one can endeavour to test the position, by obtaining data regard- ing atoms, on the basis of some hypothesis as to the way in which they combine chemically. It has been shown in this paper that Dalton, so far as the formation of the chemical theory is concerned, did not act on the belief that atoms of different kinds have the same size. Again, the author has already shown, in the paper on Dalton's physical atomic theory, that the chemical theory was formed first and the conclusion that "atoms" of different gases were different in size was come to afterwards. This is the order that was to be expected in the nature of the case. Moreover, there is nothing in the note-books to show that the chemical theory was devised except for its own sake. The testing of the sizes of atoms was an afterthought. The connection between the sizes of atoms and the diffusion of gases was not con- sidered till a year after the chemical theory had been formed. The cxperiuieiits of August ^th, i8oj. The chief matter that continues to be doubtful is the exact way in which Dalton arrived at the law of multiple proportion. The author, after a careful consideration of the evidence, can come to no other conclusion than that it was Dalton's experiments on the combination of nitric oxide and oxygen that aroused his attention, and made him apply his physical theory to the purposes of chemistry. Manchester Memoiis, J\>/. Iv. (191 1), No. 0. 15. The facts, as established by the note-books, are that Dalton, for the purpose of his inquiry into the composition of the atmosphere, was studying the combination of nitric oxide and oxygen in the year 1803. He was at work on the subject during March and April, and then again in August. On the 4th of August he obtained the well- known result that 100 measures of air could take 36, or 72, of nitric oxide.^' His first table of atomic weights was drawn up by the 6th of September. The first case of combination in multiple proportions observ^ed by Dalton must have seemed of great importance to him. His observation of August 4th, regarding nitric oxide and the oxygen of the air, is the first of the kind which he recorded. It is difficult to suppose that he can have known an earlier one. Yet Roscoe and Harden think that this case was of comparative unimportance in the development of the atomic theory. Their reason is that the chemical compounds concerned are not sufficiently represented in the first table of atomic weights. The chemical changes, as Dalton understood them, may be set out in the equations : — (i) NO + 0-=NO., (nitric acid). (2) 2N0 + 0 = NA ("'trous „ ). Certainly, if the whole matter turned on nitrous acid, Roscoe and Harden argue, it is surprising that Dalton ignored this substance in making up his table on September 6th. They suggest that the symbol for nitrous acid which appears at the side of the table was added after- wards, probably about the 12th October. Everyone must admit this who inspects the original table, or the photo- graph in Roscoe and Harden 's book. Dalton seems to have set aside the case of nitrous acid ^1 Roscoe and Harden, op. ciL, pp. 34, 38. 14 MELDRU^r, Development of the Atomic Theory. for a time as being too complicated. The union of two atoms of one kind with three of another must have appeared at that stage of thought to be very complex. Dalton did not adopt such a formula till October. On the 1 2th of that month, as a summary of his views, he gives tables of binary compounds, of ternary, of compounds of 4 atoms, and compounds of 5. Alcohol and nitrous acids were the only compounds of 5 atoms. Alcohol is ether and water united, or 2 oxygen, 2 carbon, and i hydrogen. Nitrous acid is 3 oxygen and 2 nitrogen. The objection of Roscoe and Harden, however, must 'be final, but for one circumstance : the objection ignores the physical theory. The experiments with nitric oxide ■and air must have received lengthy consideration had it not been for the fact that Dalton had an atomic theory already in his mind. As it was, these experiments simply served to give the impulse needed to set his mind working. Under that stimulus he ma.de a beginning with the adaptation of the physical theory to chemical purposes. Nothing more was needed. Larmor, in his Wilde Lecture on the " Physical Aspect of the Atomic Theory," represents that the doctrine of combination of atoms in the proportion i : i must forthwith lead to other cases such as I : 2. " Once it is postulated that only one kind of aggrega- tion into molecules occurs, e.g.., that in water there is only one way in which the hydrogen attaches itself to the ■oxygen, the laws of definite and multiple proportions are self-evident."'" Earlier in this paper, the author has pointed out how the doctrine of i : 1 arose logically from the physical theory. There are here, therefore, all the elements of a fair account of the origin of Dalton's chemical theory. ^^ Manchester Memoirs, vol. 52, no. 10, p. 9. 1908. MaiicJiestcr Memoirs^ Vol. h. (191 1), iV^^. <». 15 The germ of it is to be found in Newton's theory and in Dalton's physical theory of the year 1801, and one must recog;nise the space of two years during which it remained in the germ. There comes tlien the experiment of the 4th of August, 1803, sufficient to arouse Dalton's attention and make him apply his theory to the purposes of chemistry. He frames the rule of i : i, then considers the less simple cases, and tests his ideas by the available analytical data. By the 6th of September he is able to draw up the first atomic-weight table. Clieuiistry tvithout the atomic tJieory. Attempts have been made in recent years, by VVald and Ostwald, to deduce the laws of chemical combination from first principles, without making any use of the atomic theory.'" It seems to the author worth pointing out here that there is no connection between the modes of thought taken by these writers, and the process by which these laws were actually established. With the atomic theory as a starting point, they were formulated by Dalton and completely established by Berzelius. Moreover, at the same time and as a matter of course, the foundations •of chemical analysis as a genuine science were laid. The failure of other icorkcrs. Sufficient attention has not been given to the question, why it should have been left to Dalton to draw attention to the law of multiple proportion ? It was not the want of interest in the subject of chemical composition. The workers on the subject, towards the end of the eighteenth and the beginning of the nineteenth century, were quite numerous. One may name Bergman, Wenzel, Klaproth, Lavoisier, Richter, Kirwan, Thomson, Bucholz, Chenevix, ^^ See the Faraday Lecture, Trans. Clieui. Soc, 1904. i6 Meldkum, L)evelopmc7it of tJic Atomic Theory. Bostock, Clement, Dtisormes and Proust. Yet the failure of these chemists to discover the law of multiple propor- tion, despite their immense labours, was complete. An incorrect expla}iatio II of the failure. The reason usually offered for this failure is, that the- data for the composition of substances were calculated in such a way as to hide the law.'* Plainly the implication is, that the data calculated in a suitable way must reveal the law at once. This is mere guess-work, for as a matter of fact, data were frequently stated in precisely the way required. Proust, for instance, gives practically all his data for the oxides and sulphides of a metal, in terms of lOO parts of the metal. ^' The true explanation. The true explanation is twofold. In the first place, accurate chemical analysis is impossible without a check of some kind. That the analyst should have good intentions, even the best intentions, is not enough. In the absence of a guiding principle, chemists cannot tell when a substance is pure, or when an analysis is correct. As explained in the first paper of this series, it was this state of uncertainty which contributed at the beginning of the nineteenth century, more than anything else, to the spread of C. L. Berthollet's ideas regarding combination in indefinite proportions. Arrhenius has pointed out that every chemist noiv prepares his substances so that ^* E. von Meyer, "Hist, of Cliem.,"' Eng. trans., pp. 195-196, 1906, and Arrhenius, "Theories of Chem.,"' Eng. trans., p. 16, 1907. 15 Ann. de Chitii., vol. 28, p, 214, 1798 ; Jour, de P/iys.^ vol. 54, p. 92, 1802 ; vol. 55, p. 330 ; vol. 59, p. 324, 326, 330, 352, 1804 ; vol. 62, p. 136^ 138, 139, 1806 : vol. 63, p. 431, 1806. Manchester Memoirs, Vol. iv. ( 1 9 1 1 ), No. 0. 1 7 they agree with the laws of definite and multiple pro- portions. In the second place Dalton was at an advantage over other workers, in having a theory to which he could refer facts. Something more is needed than important facts, one must have the eye to perceive their importance. Charles Darwin gives an illustration of this when he admits he once walked along a valley, full of the plainest indications of glacial action which he absolutely failed to notice. " On this tour I had a striking instance how easy it is to overlook phenomena, however conspicuous, before they have been observed by anyone. We spent many hours in Cwm Idwal, examining all the rocks with extreme care, as Sidgwick was anxious to find fossils in them ; but neither of us saw a trace of the wonderful glacial pheno- mena all around us ; we did not notice the plainly scored rocks, the perched boulders, the lateral and terminal moraines. Yet these phenomena are so conspicuous that, as I declared many years afterwards — a house burnt down by fire did not tell its story more plainly than did this valley." "' This is not a fanciful argument, but one that can be amply justified by facts. Chemists did not go on making analyses conscientiously without sometimes obtaining data in good agreement with the law of multiple propor- tion. But they quite failed to perceive the significance of the data. Dalton himself was able afterwards triumph- antly to point out more than one such case, which had escaped the notice of the chemist concerned. He quotes Bostock's analyses of the acetate and superacetate of lead :—"< ^" "Life and Letters of Charles Darwin," 3 vols., 1887, vol. i, p. 57. '■'' Nicholson'' s /our., vol. 11, p. 75, 1805 ; vol. 29, p. 150, iSii. 1 8 Meldrum, Development of the Atomic Theory. Acetate. Superacetate. Lead lOO loo Acid 24 49 Again, he gives the instance of the oxides of carbon : "Carbonic oxide contains just half the oxygen that carbonic acid does, which indeed had been determined by Clement and Desormes . . . who, however, had not taken any notice of this remarkable result." '^ ^® Roscoe and Harden, op. ciL, p. 117. Manchester Mejnoirs, Vol. Iv. (191 1), No. 7- VII. The Behaviour of Bodies floating in a Free or a Forced Vortex. By Professor A. H. Gibson, D.Sc. Uimiersity College, Dundee. Received January iitli. igi i. Read Januaiy 24th. iqii. § I. To anyone who has watched the behaviour of bodies floating in a vortex, whether of dimensions comparable with that of the whirlpool in the Niagara Gorge or such an one as may be formed in stirring one's tea, and who has noted how some objects are apparently irresistibly drawn into the centre of the vortex, while others revolve around its outer boundary, and others again alternately approach and recede from its centre, it must be apparent that the forces producing these various results must be of considerable complexity. In a series of experiments recently carried out by the author an attempt has been made to determine how, in either a free or a forced vortex, the behaviour of the object depends upon : — {a) Its size, the depth of immersion remaining constant. {b) The linear dimensions, in similar objects of the same specific gravity. {c) The depth of immersion, in bodies of the same cross sectional area but of different specific gravities. {d) The position of the centre of gravity in non- homogeneous bodies of the same size and shape. {e) The shape of the body. (/") The intensity of the vortex action. March yth, igii. 2 Gibson, Bodies floating in a Free or a Forced Vortex. § 2. Experiments on Free Vortex. The free vortex experiments were carried out in a cylindrical tank, two feet in diameter and one foot deep. This is supplied with water through a pipe iMn. in diameter, making connection with the tank through an external volute whose centre line is six inches above the bottom of the tank, while discharge takes place through a central hole in the bottom of the tank. The intensity of the vortex action was varied by enlarging this hole from one inch in the first series of experiments to ijin. in the second series, and by varying the head of water in the tank from 9 inches to 12 inches. Throughout the experiments the motion approximated very sensibly to that of flow in a true free vortex. The motion, as investigated by colour bands, was steady and non-sinuous, and the surface smooth and free from waves. In the experiments carried out under a head of nine inches, the form of the surface profile is indicated in the following table. Radius (ins.) 12 10 8 6 4 3 2-5 2-0 I '5 i"o •50 Depth of surface below\ surface level at outer 1 circumference of tank, > in inches, with i inch 1 orifice ... ...; •00 •025 •050 •085 •13 ■19 •27 •40 •64 1-14 2"IO Ditto, with \\ inch| orifice ... ...j •00 •030 •060 ■13 •26 •43 •67 I "06 r6i 2-96 — The first of these orifices discharges "0109 cub. ft. per second, and the second 0152 cub. ft. per second under this same head. A series of experiments carried out to determine the value of the coefficient of discharge for each of the orifices MancJiestcr Mcvioirs, Vol. Iv. (1911), No. 7. 3 under heads varying from 8 to 12 inches, showed this to be sensibly independent of the head, and to have value of '287 in the lin. orifice and '178 in the iMn. orifice. The accompanying tables detail the behaviour of the floating bodies in typical cases of the experiments of each series. The following appear to be the main conclusions to be drawn from the free vortex experiments. (a) Floating particles whose dimensions are very small compared with those of the orifice, rotate in spiral paths approaching with a continually increasing velocity, and finally disappearing down the funnel of the vortex. The rate of approach of such particles is sensibly the same as that of the fluid itself. (In the second series of experi- ments such particles, of sawdust, described about 40 revolutions while approaching the centre from 9 inches radius.) The lighter particles, however, show a distinct tendency to approach the centre more rapidly than those of a higher specific gravity. ((^) If of dimensions which are moderate compared with those of the vortex, the behaviour depends largely on the shape, size, weight, and position of the centre of gravity of the object. In every case the latter rotates, about its own axis, relative to the surrounding water, in the opposite direction to that of its revolution around the centre of the vortex. If introduced near the periphery of the vessel it usually approaches the centre, and may either settle down to rotate in seeming equili- brium at some definite radius,alternately approach and recede from the centre, or straightway dis- appear down the funnel. 4 Gibson, Bodies floating in a Free or a Forced Vortex. o .^ ^ > ' o =- t/3 r- n) *^ a, r9 o a; 00 ■5 o ^« r-; 1) Tl ■j:^ (J o O (U ■ r- 'U % n a 'O "^ c Q) o 4-» r-i lU C/J O r- C •- 2 ^ CJ T3 fe: OJ (L) ,— < 1- o •'- --ixi^ T-! (N CL, H ■'5 en > ri r^ > (/I . p^ D tn -^3 S-H a; tn o T7 % rt rt ^W i~ Jii o r rt > _ OJ ^ £ 'O CO - ^ c rO •*-■ .,_> en .- ^ >- 2 'f' ?■ rt 3 ■*- . 2 o-^ _ I— I P 3 C ~ "-5 O « o o ^ o "^ 2 3-^3" ^ u^ p^_ y.^ 'u ;> v4^ j^ vt/ ^ o C3 T3 - C rt 0) c u u u u u 3 f-; ^ OJ ro j::i en C in > o ri c •n •^ 3 «> on Tl rt •n r! r-; -a ^ 3 t/i JZ to 3 ;_ (1) •*-' -n >-. (t! ^ !>. in s-< ON a; o t^ ns U & in CI, OS .— . T^ t/) , t CU Dm CI, 3 o rt C.5 "U c/5 en p; in • — . nl ■ r' Tl ■f 2 2-1 "-^ix^^^ 2 rt cJ nj o c ■ 53 " " - P 2 ^ ^ ^'x ■^ (J j:^ 2S--I — in ;? o Manchcsicr Memoirs, Vol. Iv. ( 1 9 1 1 }, No. T. ^ qj .y « rt 2 ,^ c >- t" c 3 •" TJ ^ <, CU y' C "" ^t '-' ■- ^ i: ai "^ *- .»-j >-^ o ^ C (N > rt *"• !- -^ X X X X X X X = to : O OJ ^ ^ J= O ~ Td --^ rt ", o C O '- - (Ai t/3 03 _ --o-^tuo-iecc; —J ^-1 — ' o o > •" -I ^ .2; OJ ^ > ^j ^ t:; >%"-g .;" 13 o, '- O O 3 1; 1—1 S -55 -^ « c '-5 .-/^ O ?3 C oj r- r- C tj." o .2^ o_^ s o « ^ . ^ ^ -!» - G - ^^ oixii; ^ o '^ M t« ^ c '— qj d C X rt S S o^ o^ < 13 ^ X U Cl,>^ ^ \ ^ rt ."ii c 0 -^Mlco Q U3 5 i= 13 ■" r^ 0 OJ t" ,^ 0 « rt C/2 >^ 4^ ^^ — >~ ^ (U 0 n r^ inde ded ntral 13 ID CD d, n (yj a^S " >, 0 t; r: c"d ti 0 p 0 y ii r i 5 .5 0 ^ c -^3 ::! q A '> o o ^ S 13 "" - • C/2 O *-■ ^ ^ 13 ii o <1J =- ^ rt o i! O OJ 1^ Q OT ij r- oj •^ 2 > c S 0 i^ S^ 0 cj 0 ID >. -^ g.-S 3 13 *-! cS ^ t" r-i t/5 ID .- D >- ID fe 3 rn 2 S-6 > ■"a! r/-, _ 0 .- a '^ j= •'- -3 t« ;:: ^ ^ 13 0 0 (^^"r 13 &: t/ 0 rrt D 13 '3 o ,^ 0 -'.'C'l t: t t t ►- ►"I rlI'^rH|-^i— tJTjl X X CU XXX a 0^ t/3 t ;; ■^I'Mtt t N N M — HiN C/3 13 o . O 10 J-, > S 2 10 N ro -1" 10 O t^ 6 Gibson, Bodies fioating in a Free or a Forced Vortex. ?: -r o 3 rt 3 ■2 > en "XJ .^^H^-a 2 3 rt ^ '-' -^ rt rt rt ii Ti • — 13 >^ rt TJ s-» rt 03 ^ ^ O ^ •e; i-i OS O , m in rt P4 UU^ L)U o 3 "'5 s 0. u o 1) 0) ^3 0 -u ~" l^i" I'm' Iim" In" I-.i .'S - " " - ^ '•£ "^ -t '"l-o'^p^m'^ls: i-.i Hm 1; .-hItJI CO M H- M coHl'.-l'M CO M - ro - -H CO o "5 -^3 3 fcfl Pii 00 Os O — M C) ri ro ro ro -r) 0 (■■) ,.— ^ > ^ ■OJK 0) 3 to CI J ?. c: (ii 73 '^ ■^^ QJ W 0) uo 'O ^ ^ 0 rt (/5 OJ c! r > •C' rt biD -i^TI 0 0^ ^ <--. 0 C3 0 0 0 0 0 J^ . C)Q 0 " ^ "1- C 73 ^■1— t r^ t/3 rt ]\Ianc)icstcr Memoirs, Vol. Iv. ( 1 9 1 1 ), No, 7. i^ d 'rt . tX) ^„ <^ 0 ^ '"' r^ 2 0 ^ . '"^ — ^j — ' X r- 0 OJ C —' 2JS 0 dius ly wo own s-^-^ any radu awn > :; :: " - ^ ^ ^^ — :i crr*.-oioo a i CO -^ rr 1-1 w t^ 75 r^ S 0 % „ ^ .— . D — -HM ^ '^ ,— t "n =t M 0 r^lTc rz: OS T3 ^ 5 "" r- 0 il t/3 ^ _ "— 3 n ^ ^ ^ ^ 2 s'-S ■^ .2 ns ^^ "■ C/3 5£ rt (/5 — t- in OT ^ ■^ C ■" •" D -i-> CO 0 rt 5;^ 5 •*- r; OJ &,h-i •~ ;; ^ ^ ^ r> 3 < Q- P r^ 5 •^ -^ rt " r. rx ^,^ 'O '-5 ^ ::; i; ^ t t t ^ ^'.-t* C^.^^C^^i* KiTt* CCW c-.rf Ki-j-c: ^ X X X X X X XX bfi to ^ » •« ^ r^ rN n •. ^ ^ r^ 0 •^ *x -» -N :j ^ J, t t ^l-l* t :; t rH]-^i- 3 ■* ■^ ^ 0 rt 0^0 ircular loaded a to float V niersed. a; 5 ■^ 0 0 0 U U — G G fO •+ m ^ i^ 00 00 ^ T '^ -t T rr -^ ir-. u -a c 3 o X! ho :3 o Ui 4:: -M ho c 'hb rt XJ u to U o > pq <: c D 0 -, r- QJ in •"SO. T3 c 3 >^ - & i2 0 <-. — .ri •n 0 r^ C'-'-X) 1.OI00 "^ rj ■ ^^ CM ro • ^ t3 r:: S QJ 0 0 i3 _o . 3 -^ 1/5 rt "i-* ^ ^ 'O p ■^ & S rti^ I.— '"' X H- ( (U 1-1 „ QJ rt .3 -2 QJ 0 t/5 -i«J ^ > _3 '5 -a > QJ 0 tf] ?s (/) QJ - QJ 3 ■'3 i W) t/5 r^ rt H!^^ D 3 .E '"' •" OJ ii 0 a Him '5 rt C3IC0 t^-jO t- -' E -i-n rt - (J i- CJ D u U •^y* 1— H 0 ^ ^ „ , ^ -1 ^ l:i " b< " |c> "|j ^ -.-J '^i^ "ira ■^1::. p X X X X X ^ rt TD ^ ^ »-:?! J ^ "r-n V) ►— ( -" «h 0 : • t/- -d "3 a 0 ^ P „ ^ „ , rt 0 i^ a a CJ U HH N r^ ■+ u- 8 Gibson, Bodies floating in a F/rc or a Forced Vortex. in Si o C o X! o x: J3 o bo bO ns U X5 O > U pa n o:! ^^ o c > CN c o P o O -a C/3 m 4J ' '"' uo O [/5 (U t/) )-> Tl C C fO CU >^ ^ •= < ^ lU 3 •^ .2 ^ -t; .— • — 1) T3 T3 «^ — *" " '5 '5 C/2 73 " " rt CD rt :-- 3 3 0 3-, 3-1 ^ >< rt o "'5 > 4-> qj rt 0 T3 rt - 3 cr ^ ,-Hl^- C7N 0) CO CO r^ ,fc_, CJ rt a 0 <]i a, 0 r^ .t_, "^ -O en ^ c/2 .5 O S 2 a ■-5^5 ON ON rt CIh Cui k ^ 0 tn 0 ■ 3 ^ TJ Tl 5 rt r^ 0) :-< S rt u _o rt t3 a, en p rt "^ CO ro rt (/o O — CI4 rt CI. > 2 > O rt en ^3 '3 ^ '5 S ^ o ^ 4=. rt 'O rt T3 bb o So ^ TD CI, „ Qh >: rt CD ^ CO .3 O — CJ o o 3 -^ S -:^ •ti 2 S 2 o G U U f^CO Cn o o CO Ji Manchester Memoirs, Vol. Iv. (191 1), N'o. H. g C C .r-. ^ 3 ■p Ph rt is 1/5 ^ • r- ^ 1— t .- o; 'O *" r- ^
  • "^ 2 rt|-i -li-' <^ C t/i "^ "^ tJfD i-!x u:|xr-+^ rt ^ 0 - C - - i" M l-l 1-1 N h-i ■-' 0 CL, " j; " " " c- 0 '^ ^"O rt Oh G • r-, .i '^ ^ ^ - -. ■s , .. ^ 0 rt -^ 0 0 " " ':i in -> 1-. rt rt ^ "w '-o 0 "0 " c> "cN "c> "as "c^ ~c^ ^CN^cs "os ut in at rt rt rt rt IT) ^ cn C 3 to Cl, C C ij Cu Oh u 'O „ „ „ „ „ H ^ ^"^ '? '5 " -- " ;^'5i 37* " ►» "-I rHllJHl'Hrllei (-( mloof-H'H-^n-.iTi' — hH aJ ^ ^ ^ ^ X X X X X X X X X X X X x?= X XX X ^ v tii^ " " bfi rt c « ^ 0 -'■--- p ° X 0 -^ -V *> CT' '"" CO ^ ? -*-i; ; -I-' ; ; ; i ; ; H^ Hri* ^l-^H-i* ^tJ( PD M -. «^ M -. n n M w w;ri CI ro ^r CO to CO 0 in E 0 -3 -^^.0 0 0 tn 0 S -§ d. 0 3 'S'^ S C/3 0 0 3 -i-> :::; (U -3 rt rt r^ — 73-4:; >: ^>rt > § 2 2 rv2^ % •;5 5 C/3 v5 2 bC OQ Q « "G ■ 0 0 \o ss ■ 2 rt §1 0 . ti CI, 0 0 CO 0^ 0 i-i N CO ^ u-)vci r^oo 0 0 >- M ro •^ U-) vo « *-! M M 0 M C-) M PI C-i M C4 CO fO CO rC to rO ro 10 Gibson, Bodies floating in a Free or a Forced Vortex. (i) Where homogeneous bodies have the same specific gravity, depth of immersion, and shape of plane of flotation, generally speaking the larger shows the greater tendency to approach the centre. In bodies, the section of whose plane of flotation approximates to a rectangular form, this appears to be generally true, but in circular cylindrical bodies floating with vertical axes, there appears to be a critical diameter, — from lin, to i|in. in these experiments — for which the repellent effect of the vortex for small radii of revolution is very marked. Objects, whether of a greater or less diameter than this, show a greater tendency to be drawn into the vortex, though this effect is more marked with increasing than with diminish- ing sizes. Cf Experiments A (i to lo) ; B (i to 5) ; C (i to 9). The same applies, in a lesser degree in the case of bodies of square section, but here the critical size appears to be somewhat less. Cf. A (23 to 26) ; C (24 to 28) ; A (27 to 32) ; C (14 to 17). Cylindrical objects of a size somewhat larger than, but approximating to the critical, appear to have a definite circle of rotation on the lip of the funnel, in which, except when affected by ex- traneous circumstances, they may rotate indefinitely. If displaced outwards from this circle they return, while if displaced inwards they are drawn down the funnel. Objects somewhat smaller than the critical size — from •Mn, to lin. diameter — have an equilibrium circle of much greater radius, usually from 7 to 10 inches in these experiments. The radius of the equilibrium circle for a given object increases with the intensity of the vortex. For objects of greater size than the critical, it increases, within limits, with the size of object, the largest object to have an equilibrium circle in these experiments being of three inches diameter. Manchester Memoirs, Vol. Iv. (191 1), No. 7- n (2) Where similar homogeneous bodies are of the same specific gravity, the larger tends to approach the centre more rapidly. Cf. A (16 & 17), (8 & 14) ; C (12 & 13). (3) In bodies of the same shape and size but of different specific gravities the lighter tends to approach the centre more rapidly. Cf A (12 & 16), (18 & 19), (7 & 21), (39 & 40), (46, 47 & 4S) ; C (9 & 10), (30 & 31 j, (34 & 35)- (4) In non-homogeneous bodies of the same size, shape and weight, the lower the centre of gravity the less is the tendency to approach the centre. With the C.G. sufficiently low down the body gradually works out from the centre of the vortex. Cf A (19 & 20), (40 & 41), (43, 44 & 45); C (10 & II), (31 & 32), (35 & 36;. Com- paring A (21 & 22) it appears that the relative lightness of cylinder 22 more than counterbalances the change in the relative position of the centre of gravity as compared with cylinder 21. In homogeneous bodies of the same size and depth of immersion, those more nearly approximating to a circular form of cross section show the lesser tendency to approach the centre, the difference becoming more marked as the size increases. Cf A (i to 6, 27 to 32 & 33 to 38) ; (8 & 23), (12 & 25), (23 & 39) ; C (i to 5, 14 to 17 & 18 to 23) ; (24 & 30); (7 & 24). In vortices whose intensity is increased by increasing the quantity of water discharged, either by increasing the head or the size of the discharge orifice, the observed phenomena are intensified. For bodies revolving in Since in a free vortex vof , this force r becomes directly proportional to r — r^, and in- versely proportional to r'^. Owing to the in- creasing inclination of the body as the centre is approached r—i\ increases as r diminishes, so that this effect varies inversely as a higher power of the radius than the fourth. If the intensity of the vortex be defined as the velocity at a given radius, this action will evidentl)^ vary as the square of the intensity. (3) The fact that, since the velocity of the water varies inversely as the distance from the centre, there is a relative motion of water and solid, in the direction of revolution, over that portion of the periphery marked nba in the Figure, and, in the opposite direction, over the periphery marked aca. This causes the body to rotate about its own axis relatively to the surrounding zvater^ in the opposite direction to that of its revolution around the 14 Gibson, Bodies floating in a Free or a Forced Vortex. centre of the vortex. Since, however, in virtue of its revolution, the object makes one rotation per revolution in the direction of revolution, the absolute direction of rotation will usually be in the same direction to that of revolution. This rotation, relative to the surrounding water, has indirectly, an important bearing on the behaviour of the object. To realise this it must be remembered that, other effects neglected, the body tends to gravitate to the centre of the vortex, in virtue of the inward spiral flow. But over the periphery aba (Fig.) the velocity of the surrounding fluid is greater than that of the body, and in virtue of the rotation of the body, this flow will be deflected inwards towards the centre of the vortex. Consequently the force accompan\'ing the change of momentum of this passing stream of water will have an mctivard radial component. Similarl)', since the portion acd of the body is moving past its contiguous fluid this Manchester Memoirs, Vol. Iv. (191 1), No. 7. 15 portion of the wake will be deflected outivards by the rotation,* and the corresponding force on the body will, in consequence, have an inward radial component. As, however, the relative velocity is greater over the portions of the body nearer the centre of the vortex, the resultant force will have an o?ifzi'ard rsidial component. The relative magnitude of this is likely to be greater the larger the diameter of the body, and the greater its depth of im- mersion ; and, for bodies of different shapes, is likely to be least where eddy formation in the rear of the body is least marked, and therefore, with bodies of a more or less circular cross section. Since the magnitude of these forces will vary approxi- mately as the square of the velocity, it will vary approxi- mately as the inverse square of the radius in a vortex of given intensity, and as the square of the intensity where the latter varies. Where the resultant of all the forces hitherto mentioned tends to make a body approach the centre more rapidly than the contiguous filaments of fluid, the resistance to this motion will be greater the larger the under-water area of the body, projected in the direction of motion, and will also be greater the more the body departs from the spherical form. Still a further action complicates the behaviour of a floating bod}'. Owing to the friction of the lower layers of water over the bottom of the containing vessel, the velocity of whirl at a given radius is less than at points in the same vertical but nearer the surface. The centrifugal force of the bottom particles thus becomes insufficient to counter- balance the tendency to inward flow caused by the super- • These deflections of the wake were shown by means of colour bands of aniline dye, escaping from small holes pierced around the periphery of a hollow cylindrical floating body, containing aniline solution. i6 Gibson, Bodies floating ijt a Free or a Forced Vortex, elevation of the outer layers, and, in consequence, the velocity of inward flow increases somewhat from the surface downwards, and is a maximum at the bottom. This increases the relative tendency to inward motion of a body whose depth of immersion is relatively great. From the foregoing analysis it appears that, depending on the relative magnitude of the forces called into play, one body may be irresistibly attracted to the centre of the vortex, a second may be actually repelled from the centre, a third may circle in neutral equilibrium at some definite radius, while a fourth, again, depending on the size, shape, and distribution of weight, may be attracted inwards to a certain radius of stable equilibrium at which there is an exact balance between the inward and outward forces, and within which the resultant force is outwards. Others again, and this is very definitely shown by the experiments, may have two radii of equilibrium, the space between being one of neutral equilibrium. § 4. Experiments on Forced Vortex. The forced vortex experiments were carried out in a circular vessel 15 inches diameter and 8 inches high. This was fitted to a whirling table and was capable of rotation at any speed up to 100 revolutions per minute by means of a small electric motor. The same series of floats were used as in the free vortex, and as a result of the experiments the following conclusions may be drawn. {a) Small bodies approach the centre with a radial velocity which is greater the greater the radius of rotation and the intensity of the vortex. {b) In homogeneous bodies of the same size and shape the heavier shows the less tendency to approach the centre. MancJiester Memoirs^ Vol. Iv. (1911), No. X \y {c) A non-homogeneous body of the same size, shape and weight as a homogeneous body, shows a lesser tendency to approach the centre. If the centre of gravity of the non-homogeneous body is sufficiently low, the body works out to the outer edge of the vortex. {i£) The shape of the plane of flotation (round, square or rectangular) has no effect on the behaviour of the object. This is, however, only true so Ion"- as the vortex is a true forced vortex, i.e., has the velocity everywhere proportional to the radius. Any acceleration or retardation of the whirlino- table, and hence of the containing vessel, caused a sensible modification of several of the pheno- mena. {e) In similar homogeneous bodies of the same specific gravity the smaller appear to show the greater tendency to approach the centre, although this effect is not strongly marked. § 5. The forces called into play in a forced vortex, while of the same general kind as in the free vortex, differ in relative magnitude, and, in some cases, in way of action owing to the fact that the velocity of whirl now increases with the radius, varying directly as the distance from the centre. A further difference follows from the fact that the fluid now moves in a series of concentric circles instead of in equiangular spirals. Thus, due to the pressure of the surrounding vortex, apart from any consideration of the position of the centre of gravity of the body, the latter would tend to remain in equilibrium at any radius, with no tendency to approach or recede from the centre. 1 8 Gibson, Bodies floatitig in a Free or a Forced Vortex. If the positions of the centre of gravity and of the centre of buoyancy do not coincide, centrifugal action, as in the free vortex, tends to produce radial motion, which is inward or outward according as the centre of gravity is above or below the centre of buoyancy, while the same general considerations as regards the effect of different specific gravities, vertical dimensions, and depths of im- mersion, hold true as in the free vortex. The magnitude of the effective centrifugal force is still given by ^ ,bs. pl'^^'^} but as V is proportional to r this force is independent of the radius of rotation except in so far as the inclination of the vertical axis of the body varies with the radius. In the forced vortex the inclination increases with the radius so that this force now diminishes as the body approaches the centre and vice versa. As in the free vertex, the magnitude of the force at any radius varies as the square of the intensity of the vortex motion. In the forced vortex, since the velocity increases as the radius there is no relative tangential velocity, and so no relative rotation of water and solid. Where, however, any retardation of the containing vessel takes place, or where a vortex is produced by stirring in a stationary vessel, there is, due to the retarda- tion of the outer filaments by friction, a tendency to inward radial flow along the bottom, accompanied by an outward radial flow over the surface layers. Also, since the tangential velocity does not now increase pro- portionately to the radius, there is a relative tangential motion of solid and fluid which results in a rotation of the Manchester Memoirs, Vol. Iv. (191 1), No. 7- 19 body, relative to the surrounding water, in the opposite direction to that of rotation. Each of these secondary phenomena gives rise to a tendency to outward motion of the object, which tendency is more marked as the depth of immersion, the size, and the departure from the circular form, of the object increase. In conclusion, the Author would express his indebted- ness to Prof J. E. Petavel, F.R.S., by whose courtesy he was able to make use of the resources of the Engineering Laboratories of the Manchester University for a part of the experimental work. Manchester Memoirs, Vol. Iv. (191 1), No. 8. VIII. Studies in the Morphogenesis of certain Pelecy- poda. (i) A Preliminary Note on Variation in U/iio pictorinn, Uiiio tiimidiis and Aiiodonta cygnea. By Margaret C. March, B.Sc (Comimcnicated by Dr. G. Hickling.) Read December i^tli, igio. Received for publication January i-jih, igii. In studying the British fresh water Unionidae, Anodonta cygnea, Llnio pictorum and Unio tmiiidus, with a view to ascertaining the amount of variation in form in a well defined modern species, several facts of general application became clear. Relation bctzvccn variation in form and environment. I. From the study of the form of U. pictorum and U. tnmidns from the collections of Mr. Standen, the late Mr. R. D. Darbishire, Mr. J. W. Jackson, and the Concho- logical Society it became evident that there were two main types of shell, the first stout and heavy with relatively long dorso-ventral and lateral axes and short antero- posterior axis. {Fig- A of Plate.) The other form was the antithesis of this. A further indication of the existence of such forms was obtained by variation curves, taking antero-posterior or lateral axis in relation to the dorso-ventral, Although the numbers were too few to give a definite proof (132 U. pictorum, 7S U. tumidics, 114 A. cygnea) yet they gave an indication of the presence of two such forms. March 14th, igii. 2 March, Morphogenesis of certain Pelecypoda. This curve had two maxima, one at 68, the other at 75, 76, 77 for U. pictonun. On looking up the geo- graphical distribution of the two forms it was apparent that those with a maximum of 76 and 77 were found either on Keuper marls or in districts where, as at Wistow CM- ow I" Fig. I. Thickness : Length curve of U. pidonim. Park, near Leicester, the boulder clay was derived in part from the denudation of a Keuper marl district. On separating out the Keuper from the non-Keuper forms, two simple curves were got, each with a single Manchester Memoirs, Vol. Iv. (191 1), No. 8. 3 maximum, corresponding to the two maxima of the first curve. The non-Keuper curve, however, still contained a second sub-maximum at 74. Investigation showed that this was largely due to forms from the New River and Thames at Twickenham, both districts in the London Clay. The latter specimens did not give such high ratios as those from the New River, possibly owing to the greater amount of chalk in the Thames. A marked discrepancy in the Keuper marl curve was modified by the removal of forms from Congleton, where the river in which they were found, although actually passing through Keuper marl, yet flows for the greater part of its course through Carboniferous beds. Forms from Evesham resembled those from the Keuper marl in outline, but not in breadth and thickness ratio. At Evesham the Avon is running through Lias, but the greater part of its course is through Keuper marl. Their removal smoothed out the curve. The curves for tiunidus gave a similar result with maxima at 74 and •66-65. In the A. cygnea curve a similar result was hinted at, but the number of specimens from Keuper marl districts was too few to make a curve as definite as in Unios. 2. Another difference of form is visible amongst the thinner shelled non-Keuper specimens. The shells from the Marple, and Burnley and Accrington {Figs. B & C oi Plate) canals are remarkable for their extreme length, and many of the Marple specimens for a forward throw of the umbo, giving a form very like the intertidal Modiolas. This altera- tion in shape occurs during the growth of the shell as is shown by the growth lines. Anteriorly the growth lines are close together, posteriorly they are far apart. This points to 4 March, Moi-phogenesis of certain Pdccypoda. the fact that anterior growth is slower than posterior, as is natural in an animal which has to plough its way through the mud. An increase in the rate of the current in which they lived would produce a decrease in pre-umbonal development, and so tend to throw the umbo forward in forms living in strong currents. Usually rivers are far swifter than canals. But the canals in which these elongated forms occur have steep gradients, and therefore many locks. Strong lock currents are felt at any rate near the locks. The fact that these forms occur in canals with strong gradients, the more modified ones in the steeper and more numerously locked canals, seems to indicate a correlation between the two facts, although I cannot ascertain the exact locality,* with regard to locks, in which the specimens occur, nor the distance to which the lock currents are felt. Current action has been shown to be responsible for the curious " Platiform " varieties from the river Foss and Lake Rudyard. {Figs. D & E of Plate>, Elongation is also produced by the quality of the mud in which they live, thick mud inducing elongation. But forms on a similar mud to the Burnley and Marple ones are not elongated as they are. 3. The relation between current and form accounts in part for the Keuper forms. The rivers of these districts are slow and so lead to the development of forms with a long dorso-ventral axis. It does not, however, account for the thickness of the shell, or the greater lateral axis. These must be due to the composition of the mud in which they are found. It is a remarkable fact that the shells examined from districts highly charged with Ca CO3 have thin shells and * The majority of the Marple specimens were obtained from the lock basins themselves or close to the locks. MiDuJiestcr McDioirs, Vol. /v. (igii), No. H. 5 are not eroded at the beaks. This last is because the h'mestone districts are unfavourable for the production of bogs, and the banks of chalk and limestone streams are not covered so thickly with vegetation as those of streams in clay districts, so that the streams in chalk and limestone districts are not charged with humic acid and the shells in them are not eroded. The greater thickness of the shell and animal in the Keuper districts seems to be connected either with the presence of humic acid, or the absence of excess of chalk. 4. Anodonta cygnca shows a remarkable change of form during growth. The once so-called species A. aiiatina has been definitely shown to be merely a growth stage of A. cygnea. The glochidral shell (= phylembryonic stage of Aviculidai. — R. T. Jackson) of this animal is exceedingly thin and has a perfectly straight hinge line when the valves are shut. The nepionic [umbonal] markings are less pronounced than in the two Uniones studied, and consist of more or less concentric ridges, varying in number and thickness. From the commencement of the nepionic stage the young animal ploughs its way through the mud, with the result that growth at the anterior end is hindered, so the posterior end develops more rapidly. The unequal growth is more marked than in the typical Uniones, probably because the shell is far thinner throughout life in A nodon. At the end of the third year the posterior end has so gained in growth on the anterior that the originally central position of the umbo has been lost, the post-umbonal region being longer than the pre-umbonal. Anodons, when moving through the mud under the water, plough along with the head directed downwards, so 6 March, Morphogenesis of certain Pelccypoda. that the hinge line is inclined forwards in the natural position of the shell {i.e., the hinge line, instead of being parallel to the tangent to the ventral surface, vertically below the umbo, would meet it at an acute angle if pro- 4 years. X 1 6 years A — space representing the lost wing. B = \vine C -«C PV Cv -ye* Fio- - Diagrams showing typical umbonal markings in ihe British fresh-vvatei Unionidre. The British species studied by no means keep to their type. Pictorums, otherwise typical, have been found with markings sometimes resembling and sometimes even identical with those of U. ttnnidus. This latter shows intermediate stages between its own type and U. pictoi'uin on the one hand and A. cygnea on the other. Young Anodons collected from the same pond or place on a river show two varieties of markings, with intermediate stages (^Fig. G of Plate). Their ornament may consist of few, well-marked or numerous poorly 10 March, Morphogenesis of certain Pelecypoda. defined ridges, so that, at any rate in these species, iimbonal markings are valueless for specific classification. Relationship amongst the British fresh-zvater Uniones. The study of these molluscs leads to the consideration of their relationships. Evidence concerning this can be obtained from two sources, viz., the early shell with its umbonal markings, and the adult shell. I. The three types of umbonal marking in the British species have already been described. The meaning of these markings is shown in the development of young Anodons. The ornament in the youngest Anodons con- sists of two rows of " tubercles " joined into a W, later the limbs widen and form a W with a short wide inner part, later still, the inner limbs die away, leaving an even ridge. This points to the fact that the umbonal markings of Anodon pass through three phases, the first resembling U.pictoruvi, the second U. tnviidus, the last being its own normal form. A similar reading of the nepionic ornament of Anodon is given in the East African forms where the markings pass on to the neunic stages of the shell. Here they start as " tubercles," which become prominent, forming a pronounced W, which is more stronly marked where it is crossed by growth lines. The inner limbs of the W become less and less marked, and the outer limbs form a wider and wider angle with each other, until they lie practically in the same line "^ ' . 2. In the adult shell the chief differences are : — (i) The absence of teeth in Anodon. (2) The presence of alation in Anodon. (3) The absence of lunule in Anodon. Ulanchestcr Memoirs, Vol. v. {\gi\), No. ^. ii The secondary character of the edentulousness of Anodon is shown by two facts : — {a) The recurrence of rudimentary teeth in young and adult Anodons. {b) The occurrence of an almost perfectly graded series in the American forms, which, formerly included with the Uniones or Anodontidae, are now mostly placed in an intermediate group," the Lampsilidae. The first members of this series have perfectly developed true Unionid teeth, the last are truly edentulous. This loss of teeth occurs along two lines. (<^) The series rtiyriopsis bialatus. Lainpsilis laevissivms. „ purpuj'atus. Cristaria Jierculea. ^British and many American Anodons. Here the cardinals pass from a flattened, modified form to entire absence, — the laterals becoming more gradually rudimentary. ij)) The series ^Lainpsilis alata. „ coinplanata. U. presstis. kA. fragilis. Here the laterals disappear before the cardinals. Thus the edentulous forms have a double origin, — the British Anodons belonging to one series and the Magari- tanas to a second. Alation is unknown in the British Uniones, but is common in the American Lampsilidae (formerly classed as Uniones), It is a remarkable fact that the development of alation is associated with the loss of teeth. These characters may be connected with habits or conditions 12 March, Morphogenesis of certain Pelecypoda. which cannot have occurred amongst the British Uniones and which must have been of a secondary character. 3. The lunule, which, absent in Ancdon, and but feebly represented in some Uniones, is well developed in some American forms and even in early, probably Jurassic, Margaritanas. In the study of the Unionidae, Mr. J. W. Jackson has noticed that it disappears with the loss of the pseudo- cardinals. This absence, then, in A. cygnca, is due to the loss of these teeth, and with it the necessity for great width in the anterior part of the shell. This last difference, then, is of a secondary character. Amongst the British Unionida^, therefore, U. iuviidus appears to retain the most primitive features both in nepionic and ephebic stages, and so to resemble the parent stock most closely. Anodoji is the most highly specialized. U. pictornin, though occasionally showing a more strongly marked W than either of the other two, yet usually has the limbs of the W undeveloped, thus leaving unconnected " tubercles." Pictoruvi and Anodon then, represent divergent cases of degeneration from iuviidus. In the former case the limbs of the W have died away, in the latter the inner limbs have become so stretched out as to form a more or less concentric line. The more prim ive ephebic characters of tumidus are seen in its better developed teeth and marked anterior buttress. The gaps between Anodo?> and U. f?n//idus can be filled in from the American fauna. Ornament in Foreign Unionidce. The history of ornament in the Unionida^ since Triassic times has been one of degeneration from fully ornamented Manchester Memoirs, Vol. Iv. (191 1), No. 8. 13 types to smooth forms. Neumayr (Neumayr 18S9), in his paper on Trigonia, says that all Unionid ornament is post- Miocene, and therefore atavistic. That can hardly be, since the Laramie Unionids are fully ornamented. He also states that the European forms are entirely unorna- mented. In this, he leaves out of account the umbona markings. The ornament in foreign forms is of three types : — {a) Forms in which it is confined to the nepionic stages (as in British forms). iji) Forms in which it occurs on the adult shell, and is either phylo-ephebic or phylo-gerontic in character. ■ {c) Forms in which a phylo-gerontic smooth stage is followed by irregular ornament, which may there- fore be regarded as phylo-hyostrophic in character. (rt) The umbonal markings show three, and probably, four types of ornament ; (i) The W-shaped ridges, shown by many N. American, S. African, and European forms (possibly excepting the Margaritanas). (2) Single V-shaped ridges, seen in some S. and N. American forms, U. nyassensis, and a form from Madras. (3) Ridges which run diagonally up to the gonal line of the young shell. (4) Possibly a type from the Plate River and Guiana. Here the ridges appear to be purely radial, but I am not certain whether they are purely radial or only a variation of the V type, which can approximate a radial type fairly closely. 14 March, Morphogenesis of cert am Pelecypoda. {b) The most definite phyloephebic ornament is seen in the forms from the rift lakes of E. Africa. U. nyassensis ornament begins as two diagonal lines joined by a concentric bar, but later alters into a V. Specimens from lake Miverw, are purely W marked throughout. In Qicadrida lachrymosa. {=U. lacJirymosus [Lea]) the ornament is carried on from nepionic stages, dying away in old age, but is more or less distinct throughout. In U. ligainentimis the ornament consists merely of strongly marked growth lines, and is clearly phylogerontic. (c) Q. PusHdosa. (t/./;/j'//^^j'/i;i" [Lea]) starts life as a smooth shell, in extreme old age it developes irregular pustules, the ornament here is purely phylo-hyostrophic. I hope to obtain further evidence on the nature of Unlonid ornament. The PJiylogeny of the Unionidce. It is impossible to study any branch of the UnionidjE without considering their phylogeny. Two possible lines of descent are admitted, — the one through the Cardiniidae, and so in relation to the Carbonicolas. This view, accord- ing to Zittel's (Zittel, 1900) summing up, is the general one. The other, and older view, gives them a Trigonid ancestry. Several points seem in favour of this connection with the Trigonias. (i) Dentition. (2) Form of the shell. The typical Trigonid dentition consists of short lateral teeth just in front of and behind the umbo, with the antero-laterals (pseudo-cardinals) supported by a strong buttress. Manchester Memoirs^ Vol. Iv. (1911), No. 8. 15 The typical Unionid teeth consist of much elongated posterior laterals and anteriorly placed antero-laterals, either without any buttress or with only a weak one. The extreme length of the posterior laterals is pro- bably connected with their greater post-umbonal develop- ment owing to their habitat in a region of continuous current. The change from typical Trigonid to typical Unionid teeth can be bridged over by American forms : — (i) U. ellipsis has sub-equal ridged teeth with the anterior strongly buttressed. (2) Tetf-aplodon ainbiguus ( = Cast alia [Lam])[Pernam- buco] has a somewhat elongated posterior lateral and an anterior buttress. (3) Quadrula trigona {=U. trigonus [Lea]) has typical Unionid teeth, but with a strong buttress. (4) Pleiirobema bigbyensis {= U. bigbyeiisis [Lea]) has teeth as in Quadrula, but with a much reduced buttress. 2. The original description of Trigonias was based on their form, with two triangular areas, the smaller, the "area" being posterior. Modern adult British Unionidae show no such distinction on their valves. It is seen, however, in Q. lachrymosa, and in the S. E. African forms. It is distinguishable on the umbones of the British and American forms. The ornament in the two groups is, I believe, similar, but this point requires further working out. The great differences in structure, viz. : — '(i) the entire absence of a lunule in Trigonias ; (2) the presence of an ant. buttress in „ (3) the absence of an accessory pedal scar in „ can be shown to be due to progressive variation, and can be bridged over by intermediate forms. 1 6 March, Morphogenesis of certain Pelecypoda. (i) The entire absence of a lunule in Trigonias seems to be associated with the position of the teeth. As aheady shown the disappearance of the lunule is associated with the loss of anterior lateral teeth. Its appearance may be connected with the forward shifting of these teeth. In Trigonia they lie close under the umbo, where the shell is naturally wide, but after they have moved forward, they get into a region where the sides of the shell lie more closely together, especially if the animal becomes elongated, and where some modification is needed to give room for the teeth. This is done by the lunule. Also the lunule may or may not be present in Uniones. (2) The link forms between non-buttressed and Unionidae and strongly buttressed Trigonias have already been given. (3) The absence of an accessory pedal scar in Trigonias is paralleled by its absence in Quad- rula. Mr. J. W. Jackson has suggested that its absence is due to the shifting of the muscle from the buttress, where it was originally attached, on to the shell. The similarity in the essential shell characters, and possibly in the ornament, together seem to point con- clusively to close relation between the Unionidae and the Trigonidae. This relationship can only be that of a common ancestry from a pre-Triassic, pre-Trigonid stock, as the Unionida: are known from Triassic times as well as the Trigonidas. The very distinct ornamentation amongst the Liassic Trigonida^, paralleled in the Triassic Myophorias and Trigonias, puts their convergence back into Permian times at least. I think it probable that the study of ornament in the Unionida; will show the presence of as distinct, and possibly as ancient, lines as in their relatives. Manchester Memoirs, Vol. /t/. (191 1), No. 8. 17 LITERATURE. Beecher. "Studies in Evolution." Grabau, 1904. " Phylogeny of Fusus and its Allies,'' Smith- sonian Institution. Jackson, R. T., 1S89. Phylogeny of the Pelecypoda. Mem. Bosto?i. Sac. Nat. Hist. Latter, 189 i. "Notes on A/iodon and Unio.'" Proc. Zoo/. Soc, London. Lea, 1870. "Synopsis of the Family Unionidffi," Philadelphia. Marshall, W, B., 1890. "Beaks of the Unionidai inhabiting the Vicinity of Albany, N.Y." Biili. iV. Y. State Mus., vol. 2, no. 9. Neumayr, 1889. "iJber die Herkunft der Unionidem," Wien. Simpson, T., 1892. "The Unionidce of Florida and the S.E. States." Proc. U.S. Nat. Hist. Mus., vol. 15. 1893. "On Fossil Unios and other Freshwater shells from the Drift at Toronto, Canada, with a Review of the Distribution of the Unionidse of N.E. America." Froc. U.S. N'at. Hist. AIiis., vol. 16. — — 1895. "Description of 4 New Triassic Unios from the staked Plains of Texas." Froc. U.S. A'at. Hist. Mus , vol. 18. 1900. "Synopsis of the Naiades." Froc. U.S. Nat. Mus.., vol. 22. 1903. "On the Relationship and Distribution of N. Am, Unionidte, with Notes on the West Coast species." Am. N'at.^ vol. 28, no. 316, p. 353. 1 8 March, Morphogenesis of certain Pelecypoda. Shrubsole, 1886. "On the Erosion of certain Freshwater Shells." Jonrn. of Conchol. Standen. "Notes on Freshwater Mussels of Lancashire and adjacent counties." Lancashire iVa/2<'ra//i-/, Apr. -July, 1909. Whitfield, 1903. "Notice of six new Species of Unios from the Laramie Group." 1907- "Remarks on and Descriptions of New Fossil Unionidse from the Laramie Clays of Montana." Bull. Nat. Hist., xix. and xxiii. ZiTTEL, 1900. "Textbook of Palaeontology," A. Eastman, P- 377- Manchester Memoirs, \\>l.LV., No.^. Plate. Flwtos by J ■ W. Jackson, F.G.S. Typical Keuper pktorum, Marple form, showing the forward throw of the umbo. Burnley Canal form. R. Foss form. L. Rudyard form. Typical non-Keuper form. G. Young Anodons, showing umbonal markings [e. coll. K. Standen], H. U. pictorum [Marple] showing tumidus like umbo. I. Typical U. pictonim umbo. J. ,, U. tumidus markings. y ' r; f V ' i showing umbonal markings approachinj; AitoJon in type. MancJiester Memoirs, Vol. Iv. (191 1), No. Vt. IX. On an Abnormal Spike of O/^/n'flglossum 7'nlgafttiu. By H. S. HOLDEN. B.Sc, F.L.S. ( Leitttier ill Botany in the Uiii^'Cfsity College, Nottingham ). {Communicated by Professor F. E. IFeiss, D.Sc, F.L.S.) Received and Read, /annai-y lotli, rgii. The Ophioglossales, comprising- the genera Ophio- glossunt, Botrychiujii, and HelniititJiostachys, have long been a subject of considerable interest to the botanist, a fact largely due to their extreme peculiarity and modification, and also to their comparative isolation from the remaining pteridophyte groups. Tlie question of the affinities of the group has always been a thorny one. Bower has considered their affinities to be with the Sphenophyllales : Tansley leaves the matter open but suggests a common ancestry with the remaining megaphyllous pteridophytes : Lady Isabel Browne considers them to show near relationships with the ferns proper, a view which receives considerable support from the most recent work, notably that of Chrysler, which brings forward the strongest evidence for this view. Their characteristic megaphylly, their stelar anatomy, and their undoubtedly fern-like antheridia and multiciliate sperms all lend support to filicinean relation- ships. The evidence afforded by Botrychioxylon, a fossil form described by Dr. Scott in his " Studies," is also of some interest. This is a Botryopteridean axis showing, apart from the internal wood, a striking resemblance to the modern genus Botrychiiim in stelar structure, and is considered by Scott to be distinctly in favour of the close relationships of the two groups. March. 21st, igii. 2 HOLDEN, Ahnonnal Spike of Ophioglossum vnlgatuni. Many of the features of the Ophioglossales are, however, essentially peculiar to themselves, perhaps the most marked being the division of the, usually, single leaf into a well-defined sterile and fertile lobe or segment. Chrysler has recently revived the view, originally put forward by Roeper, that the fertile spike represents two fused, fertile, basal pinnae of a pinnate leaf, and considers them derived by a further elaboration of the type of fertile pinna characterising Aneiinia. The anatomical evidence upon which he bases his adherence to this view, appears, moreover, to be extremely convincing and is decidedly stronger than any points so far urged against it. If Chrysler's view is to be regarded as correct, it would appear that the members of the genus OpJiio- gloss7i7ii are derived through a simple-leaved ancestor, from the pinnate-leaved common ancestor of the group, and that they represent a reduction series culminating in Ophioglossum siuiplex. Ophioglosstiin palniatiim, on this view, must be regarded as showing secondary specialisation after the assumption of undivided leaf structure. The production of a branched fertile spike, as Bower points out, appears to be intimately connected with the lobing of the frond, and indeed from the figures given by that author (" Origin of a Land Flora," p. 440, figs. c-g). there is little in the external appearance, apart from the greater projection of the sporangia, to distinguish his BotrycJiiiivi simplex forma simplicissima, from a small specimen of Ophioglossum. This projection of the sporangia in Botrychimn does not appear to be a feature of primary importance, since, according to Goebel, it has arisen owing to the pressure exerted upon the sporangial cells by the cells of the axis lying immediately beneath them. Manchester Memoirs, Vol. Iv. (191 1), No. <). 3 The fertile spike, in normal specimens of Ophio- glossum, consists of a fairly long, unbranched axis, oval in section, and bearing apically a double row of large, more or less globular sporangia. The vascular supply is apparently subject to con- siderable variation (Cf. Text-fig. III. a, b, c) but in the sporangium-bearing region it appears constantly to consist of a central, purely cauline strand, and two lateral strands, the latter of which give off traces between each adjacent pair of sporangia. The lateral and median strands are connected by obliquely transverse strands at fairly frequent intervals. {Text-fig. I.). P'-D Fig. I. The diagram lo the left represents a camera-lucida drawing of the outhnes of part of the fertile region of a sporangiophore with its vascular supply. Figs, A to E represent the variation in the vascular supply as seen in transverse sections at the points indicate!. Ophioglossnm, in common with other members of the group, is also characterised by the relatively frequent occurrence of abnormal forms, and these monstrosities have received considerable attention both from Bower and Chrysler, and others. (Cf Bower, :08, p. 438,7?^. 239, j & k). The abnormal specimen, which is the subject of the present paper, was collected some years ago by Professor Carr, from a locality near Skegby, Nottingham- shire, and he very kindly handed it over to me for des- cription. The peduncle was somewhat stouter than the 4 H OLDEN, Abnormal Spike of Ophioglossuin viilgatuvi. average, but apart from this there was nothing abnormal in its appearance : the fertile region, however, exhibited very considerable abnormality and complexity {Text-fig. II. A, B). A. B. C. F?g. II. A. Enlarged drawing of an abnormal spike S,, S.^ Main Serie<;, S3, S4 Accessory Series. B. Semi-diagrammatic diawing from opposite point of view to A. C. Slightly abnormal specimen showing rotation of sporangia. The main structure consisted of two series of sporangia, coiled spirally round the axis, these separating near the apex of the axis, and developing in that region the double row of sporangia characterising the normal Ophioglossum "spike" {Text fig, \\. A,B\ s„ s,). In addition to these the sporangiophore bore basally and laterally, a small and apparently independent fertile portion, exhibiting the normal structure, and a similar but less completely independent one, near the point at which the two main series diverged. (^Textfig. 11. A, B; Manchester Memoirs, Vol. Iv. (191 1), No. 9- 5 Judging from the external appearance of the spike there appear to be two possible interpretations of its structure. The first is that it represents two, or possibly more, fused spikes, when it would be a further elaboration of the condition figured by Chrysler for Botrychiuni {Ann. Boi., 1910. PI. l\.,Jigs. 26-28), in which the second, as well as the first pair of pinnae have become fertile and partial fusion has occurred. In the case of the specimen recorded here, if this interpretation were correct, the fusion is much more complete than any of the abnormalities cited by Chrysler. The alternative view is that the normally unbranched spike has undergone a process of division or chorisis, a feature which normally obtains in OphioglossuDi palmatuui. It may be as well, perhaps, to state here that the anatomical evidence is in complete accord with this latter interpretation. The spiral arrange- ment is a further complication, but this feature is foreshadowed, to a certain extent, in specimens such as that shown in Text-fig. II. C. These slightly abnormal specimens are apparently of fairly frequent occurrence, no less than eight occurring in the class material at the University College, this being obtained from Aberystwyth and York respectively. It was decided to cut serial sections of the sporangium- bearing region and of the peduncle, but owing to the imperfect preservation, and the quantity of air in the tissues, which even prolonged treatment under the air- pump failed to dislodge, this proved a task of considerable difficulty, certain portions shattering very badly. The material yielded, however, a sufficiently good series to elucidate the more important anatomical features. The peduncle was first examined and, as might have been expected, showed a comparatively massive and complex vascular system {Text fig. III. D). 6 HOLDEN, Abnormal Spike of Ophioglossum vulgatuni. For purposes of comparison hand sections of twenty normal peduncles were cut, at approximately equal intervals, and were found to fall into three series. The first of these, which I propose to term the " robust " type, exhibited five strands at the end nearest its union with the sterile segment, these dividing up to form a maximum number of eight bundles, anastomosing with their fellows at various points in their course through the peduncle, and ultimately uniting to form a series of five in the region of the first sporangium {Text-fig. III. ^, la-if). There was only a single specimen of this type in the number examined. The second type, comprising sixteen of the twenty, and which 1 propose to term the " normal " type, showed roughly the same features as the first, commencing basally with five bundles, but exhibiting divisions and anastomoses which were less, both in number and frequency, than those of the first type. In the region of the first sporangium this type also exhibited five bundles in transverse section {Text fig. III. i?, la — 2/). The third type, under which the remaining three peduncles are included, is smaller than the others, and may be termed the "slender" type. In it the basal number of bundles was three. There were no signs of anastomoses, and the lateral bundles each divided once giving rise to five, at the commencement of the fertile region, as in the remainder {Text fig. III. C, ^a — 3^). An examination of the appended text-figure {Text-fig. III., A, B, C) will serve to demonstrate then, that, though there is considerable variability in the number of vascular strands in the lower portion of the peduncle, the number entering the fertile region is very generally five. Manchester Memoirs, Vol. Iv. (191 1 ), No. t>. 7 B. C. D. Fig. III. A. Series of sections through a peduncle of the "robust'' type.' B. ,, ,, ,, " normal ' ,, C. ,. ,, ,, ''slender" „ Z). ., ,, the ijeduncle of the abnormal specimen. (All tl»e diagram outlines and the relative sizes of the bundles sketched with the aid of a camera lucida. ) 8 HOLDEN, Abnoyjual Spike of Ophioglossum vulgatum. Two other points are also worthy of mention, the first being that there is, throughout both sterile and fertile parts of the spike, a dominant median strand, and the second, that, a little way below the point of union with the sterile assimilatory portion, the vascular supply con- stantly consists of three strands. The results obtained are thus in complete agreement with the work of Camp- bell, and of Holle, upon the subject. The peduncle of the abnormal specimen was in exact agreement with the normal forms as regards the posses- sion of three vascular strands before separation from the sterile segment, and in having five strands immediately above the point of separation (Text-fig. IV. Text-fig: \\\.D,d,a). Fig. l\\ Tr. S. petiole just previous to the separation of the three traces (/j, /.,, ^,) to supply the peduncle. A very short distance above the base, however, the strands subdivide rapidly, until the number is considerably in excess of even the most robust of the typical specimens. Apart from these features, there is nothing abnormal in the behaviour of the vascular supply until it reaches Manchester Memoirs, Vol. Iv. ( 1 9 1 1 ), A^^. !K 9 the reo^ion in which the small basal spike is given off. Here the bundles on the side nearer the spike divide up further until there are fourteen bundles shown in transverse section {Text-fig. V., i). Those destined to supply the lateral spike now bend round and are nipped off gradually from the main system to form an accessory one {Text-fig. v., 2, 3). The small spike was cut off just above its base, and found, on sectioning, to exhibit a structure identical with that of a typical specimen. A comparison of Bower's figures illustrating the supply to the lowest fertile spike in Ophioglossum palmatum, and the first three diagrams in Text-fig. V. will illustrate the striking parallelism exhibited by the two cases. Sections further up the stem revealed the fact that the subsequently produced structures {Text-fig. II. B, j,, ^-4) also conformed in a perfectly clear manner to this type of branching, differing only in detail, whilst the portion s was found to be equivalent to the upper portion of the normal Ophioglossum spike, representing the continuation of the main axis. It therefore appears that the specimen described represents a single fertile spike, which, by a process of chorisis, has given rise to the branched condition typically found in O. pahnatmn. A further point in support of this view is afforded by the perfectly normal character of the vascular supply to the parallel series of sporangia. Had these been the result of the fusion of two independent axes, either the vascular strands of these axes must have rotated correla- tively with the sporangia to produce their vascular supply, or, in the event of there being no rotation, those sporangia on the side remote from the parent axis would have been devoid of vascular supply. A careful examination of the whole series has con- vinced me that there is a perfectly normal vascular supply, 10 HOLDEN, Abnormal Spike of OpJiioglossnni viilgatinn. Fig. V. Nos. 1-3 show the gradual separation of the vascular supply to the Imsal sporangiophore branch. No. 4 shows the Inindle supply to the sporangia on both sides of tlie main system. Nos. 5-9 show stages in the formation and separation of the remaining branches. (All figures drawn with the aid of a camera lucida.) t;v,^„,;r.rT tVio /i«to;i ^r iK» K.in,^ii tKo loft =\A^ Manchester Meinoiys, Vol. Iv. {\gi\), No. 0. ii that is, that there is one strand passing between each pair of sporangia throughout {Text-Jig. V. 4). The spiral arrangement may therefore, quite reason- ably, be regarded as a secondary modification, admitting of the insertion of an unusually large number of sporangia, and probably correlated with the crowded arrangement of the parts. One last point in support of this view is that, though the number of vascular bundles throughout is considerably in excess of the normal, this is to be regarded as a necessary concomitant of the extra demands placed upon it, the characteristic, dominant, central strand being readily distinguishable from base to apex and terminating the main fertile spike. Summary. 1. The specimen represents a condition of the fertile Ophioglossaceous spike derived by a process of splitting or chorisis. 2. Its robust character makes great demands upon the vascular supply and this is increased pro- portionately. 3. The view that the specimen has arisen by chorisis and does not represent two fused axes is supported by the following anatomical features : — i. There is a single dominant median strand throughout. ii. The sporangial vascular supply is normal. iii. The vascular supply to the accessory spikes is in close agreement with that figured by Bower for Ophioglossuni palmatum and 12 HoLDEN, Abvormal Spike of Ophioglossuni vulgotuni. supports his view as to the morphology of the fertile spike in this form. iv. The vascular supply entering the peduncle from the petiole consists of three strands, of which the two lateral ones divide once, thus giving rise to five strands, as in the majority of normal spikes. In conclusion, I should like to express my sincere thanks to Professor Weiss, for his kindly help, to Mr. S. Garside, B.Sc, of the Victoria University, who has examined the specimens oi Op/iioglossuju in the herbarium of the Manchester Museum, on m\^ behalf, and to Professor Carr, of the University College, who gave me the specimen, and in whose department the work has been, done. Manchester Moiioirs, Vol. h. (191 1), No. 0. 13 BIBLIOGRAPHY. Bitter, G. : " Ophioglossacece." Engler and Prantl. "Die Natiirlichen Pflanzenfamilien," pp, 449-472, igoo. Bower, F. O. : " Studies in the Morphology of the Spore-pro- ducing members, ii. Ophioglossacese." London, 1896. Ophioglossnm simplex. Ami. Bof.,vo\. 18, igo^. " Origin of a Land Flora." Chap. xxx. Ophioglossace^, London, 1908. Boodle, L. A. : " On some points in the Anatomy of the Ophio- glossacese." Ann. Bat., vol. 13, 1899. Browne, Lady I. : "The Phylogeny and Inter-relationships of the Pteridophyta, Ophioglossaceie," N'eiv Pkyt., vol. 8, 1909. Campbell, D. H. : " Mosses and Ferns." Chap. vii. New York, 1905. " Studies on the Ophioglossaceoe." American Naturalist, vol. 41, 1907. Chrysler, M, A.: "The Nature of the Fertile Spike in the Ophioglossaceae." Aim. Bot.,\o\. 24, 19 10. Farmer, J. B. and Freeman, W. G. : "On the Structure and Affinities of Helminthostachys Zeylanica.'' Ann. Bot., vol. 13, 1899. Goebel, K. : " Organography of Plants." Part II. English Ed., Oxford, 1905. HoLLE, J. G. : " Ueber Bau und Entwicklung der Vegetationsor- gane der Ophioglosseen." Bot. Zeit., vol. 33, 1875. RoEPER, J. : "Zur Systematik und Naturgeschichte der Ophio- glossaceie." Bot. Zeit.. vol. 17. 1859. RosTOWZEW, S. : " Recherches sur l Ophioglossnm vulgatum." Bot. Centrall)l., 1892. ScoTT, D. H. : " Studies in Fossil Botany." Part II., Chap. xiv. London, 1909. Tansley, a. G. : " Lectures on the Evolution of the Filicinean Vascular System." New Pkyt., vols. 6, 7, 1907-1908 Manchester Memoirs, J^ol. Iv. (1911), No. 10. X. The Boric Acids. Rv Alfred Holt, M.A, D.Sc. Rereived and Read Felniiaiy Jist, igi i. An examination of the results of the researches carried out on the anh\-clrous borates of the alkaHes and alkaline earths gives evidence of a number of compounds derived apparently from some more or less hypothetical boric acids in addition to those which are usually accepted as having a definite existence, i.e., the ortho, meta, and pyro varieties. Ditte {C. /v., 1873, 77, 785, 893) described compounds of the types 2MO.3BA and 3MO . 2B,0,^, where M represents a metal of the alkaline earths, but Guertler i^Zeit. Anorg. C/ieui., 1904, 40, p. 337) has since shown that these represent eutectic mixtures. This latter author has found evidence for the following compounds : (i) 3MO.B.O8, when M is magnesium or barium. (2) 2MO.B.O3, when M is any of the alkaline earths. (3) MO.B,0, and M0.2B,0,, when M is calcium, strontium or barium. The present writer has found that in the case of the sodium borates, compounds of the composition NajO . B.O^ and also probably Na,0 . 4B.,0, exist, while the anhydrous stable crystalline form of borax is an eutectic mixture (Proc. Roy. Soc, 1902, 74, 285). ApnV 20th, igii. 2 Holt, TJie Boric Acids. • Very little attention seems to have been paid during recent years to the boric acids, and most of our knowledge of these compounds is due to the researches of Ebelmen and Bouquet {Ann. C/iiin. Phys., 1846,3, 17,63), Schaff- gotsch {Pogg. Annal, 1859, 107, 430), and Merz(/. Prakt. Cheni., 1866, 99, 179). Ebelmen and Bouquet, by examining the rate of dehydration of orthoboric acid, concluded that at least two other acids existed, and in support of this view described organic derivatives analo- gous to borax, and an orthoborate. Schaffgotsch observed that when orthoboric acid is heated on a water-bath for some time, two-thirds of the water it contains is removed, leaving a vitreous substance which could only be deh)'d rated completely by heating to a very high temperature. Merz confirmed the observations of Schaffgotsch, but considered that several acids containing less than a third of the water of orthoboric acid existed. He also noticed that orthoboric acid was volatile to some extent in the water vapour given off on heating it. The molecular weights of neither the anhydrous borates nor meta and pyro boric acids are known, and consequently their formulas are only empirical, but the constitution of the ortho acid is well established since it forms a volatile triethyl derivative. The experiments described in this paper were carried out to see whether the meta and pyro acids were really definite compounds or mixtures, and whether any other acids existed. In the first series of experiments a weighed amount of orthoboric acid was heated in a platinum dish at a constant temperature and the loss in weight determined from time to time. Mandicstcr Memoirs, Vol. Iv. (191 1), No. 10. 3 (i) Temperature, 98°C. Weight of acid taken =3'89 grms. After heating for 24 hours, weight = 2,"hS » » » » 46 ,, „ =3'o7 » '> j> )) 95 >' ') =274 „ )' 1) !) 118 ,, ,, =274 ,, » ;, •, 125 ,, ,, =274 ,, 3*89 grms. of orthoboric acid yield 276 grms. of meta- boric acid. The loss of acid through volatilisation is very small. (2) Temperature, i2o°C. Weight of acid taken =4"22graiP. After heating for i hour, weight =4Tf „ 1 J h ours 11 = 4-04 6 11 )' = 3-S7 10 11 M = 371 14 11 )) = 3 "49 19 >) )) = 3"23 25 r 11 = 3-01 30 11 11 = 2-95 42 )) )> -2-94 52 )) )) = 2-94 422 grms. of orthoboric acid yield 3 00 grms. of meta acid. The amount volatilised in the water vapour is somewhat greater in this than in the previous experiment. This is probably due to the temperature being higher and the rate of dehydration being consequently faster. (3) Temperature, 150'C. Weight of acid taken ... ... =4'i4grms. After heating for i hour, weight =278 ,, J> )i )J 5 " " 2 DO ,, >> )) )) " >> )) ~ 2 54 )) )i )) )) ' 3 " " =2 47 11 )) )) )) 29 )) 1) ""232,, 5j J) jj 37 )) !> ~ 2 20 „ Mult, The Boi ic Acids. So ko - ie \ \ \ c 1 3 Time in Day- Iv.^. I. 1o io Time in Hours. Mi^\ 2. MancJicsti'i- Mcinoirs, Vol. h. (191 1), No, 10- 5 4 14 grms. of orthoboric acid yield 292 grms. of metei acid and 264 grms. of p)-ro acid. In this case the loss through volatiHsatiou is much greater, the final product weighing less than the tlieoretical amount for boric anh}'dride. It would, therefore, seem that the amount volatilised depends upon the rate of heating. These three experiments, only calculated to show the percentage of water present in the compound from time to time, are shown graphically in Figs, i and 2, from which it will be seen that only one break exists in the deh)-dration curve. It will be noticed in Figs, i and 2 that the break in the curve occurs with a lower percentage of water as the temperature at which the experiment was conducted was raised. This is due to volatilisation of the ortho acid in the water vapour. The difference between the percentage of water present in the compoutid when the break takes place and the theoretical value for metaboric acid (205 per cent.) gives a rough measure of the volatility of the ortho variety. These results confirm those of other experimenters as to the marked change in the rate at whicli the ortho acid loses water, and probabl\' show the definite existence of metaboric acid, but there is no indication of any other compound. I'he second series of experiments consisted in the determination of the melting points of mixtures of ortho- boric acid and boric anhydride. Intimate mixtures of the required composition of the two substances in a fine powder were made, and then introduced into stout capillary glass tubes, which, as soon as they were filled were sealed as close as possible to the top of the mixture. The melting point was then determined in a bath of sulphuric acid. It was necessary to use sealed tubes as 6 Holt, The Boric Acids. ^ the orthoboric acid would otherwise lose its water on heating. The following results were obtained : Orthoboric acid (H3BOJ melting point 169-170 . 2H3BO3. BA >> M 158-159*- H30,. B„_0, „ „ 159-160*. 2H30,.3BA M " 167-174°. H^BCK.aBA ,. >. 172-173'- 2H30,,.5BA: » n 171-173"- H,B03.3B,0, „ „ 172-174". H3BO3.4BA " " I7I-I72^ H3BO3.5BP, „ „ 170-172". These results do not point to any definite compounds. When boric anhydride is added to orthoboric acid, the melting point of the latter compound is lowered. It subsequently rises again and then remains approximately constant. In all mixtures, containing more boric anhydride than is represented by the composition HjEO^.B^Og, a small portion of the mixture melted at 158 -159", the melting points given above being those of the main mass of the substance. It is possible that this is the result of imperfect mixing of the constituents in the capillary tubes employed, but more probably is due to the formation of two partially miscible solutions. Mixtures richer in boric anhydride than is represented by the composition H3BO3.4B2O3, when melted remained on cooling in the vitreous meta- stable state, for when heated to i lo'-i i S'' they gradually but completely crystallised. Boric anhydride itself could not, however, be obtained in the crystalline condition. In this connection it is interesting to note that metaboric acid apparently exists in both vitreous and crystalline states. When orthoboric is heated in air for some time at 100° an almost completely vitreous mass of the composition repre- UTaiic/ies/er Meviflirs, Vol. Iv. (191 1), A^^. 10. 7 sented by metaboric acid results. If this heatins:^ has, however, taken place in a vacuum, the water evolved being absorbed by a drying reagent, the metaboric acid is a dry amorphous powder. Further, when a mixture of boric anhydride and orthoboric acid in equimolecular proportions is fused under pressure, a crystalline mass results. The changes in vapour pressure on heating orthoboric acid were next examined. The first experiments were carried out at 70°C. The vapour tension of the acid at this temperature remained almost perfectly constant for many days, when it suddenly dropped to about one-fifth its original value. When this drop in pressure occurred, a portion of the material was withdrawn and analysed, when it was found to contain 23'4% water. (Theorj^ for metaboric acid 20'5 %.) The rest of the material was then heated to i8o°C. and the further changes in vapour pressure observed. It was necessary to employ this high temperature as the vapour pressure of the meta acid would otherwise have been too small to observe. The observations at i8o°C. were inconclusive as regards th formation of other compounds. The vapour pressure steadily decreased with time, and, though this decrease was not at a constant rate, no definite and marked changes occurred. Some experiments were carried out by the freezing point method on the molecular conditions of the boric acids in aqueous solution. Three portions of the ortho acid were heated till one had the composition of metaboric acid, the second pyroboric acid and the third was com- pletely dehydrated. Solutions of these portions, as well as the ortho acid, were then prepared of such a strength 8 Holt, The Boric Acids. that each might be considered to contain the same amount of boric anhydride per c.c. of water. The freezing points of these sokitions were the same and identical with that of orthoboric acid, this condition remaining unchanged whether the sokitions were very dilute or almost saturated. Solutions of orthoboric acid from 2'48 grs. in lOO c.c. water to O'l gr. in lOO q..c. water gave depressions of the freezing point in accordance with a molecular weight of from 685 to 55 (theory for orthoboric acid (i2). The acid was apparently- very little ionised. No solvent could be found for either boric anh}'dride or the other boric acids, in which they did not undergo change, so their molecular weights are unknown, but from the fact that the\- are vitreous substances in some ways analogous to the phosphoric and silicic acids, their mole- cular weights are probabh" greater than those represented by simple molecules. Orthoboric acid is readil)' soluble in hot glacial acetic acid, from which it separates out unchanged on cooling. Boric anhj'dride does not appear to be soluble in this acid. It was hoped, by means of this difference in behaviour towards glacial acetic acid to decide whether the meta and pyro acids were mixtures of the ortho acid and boric anhydride or not. Metaboric acid dissolves to a very slight extent in hot acetic acid the solution depositing the ortho acid on cooling, but the amount dissolved is far too small to correspond with that required for the meta acid if this compound were an equi-molecular mixture of the ortho variety with boric anhydride. The pyro acid does not seem to dissolve at all. From the experiments which have been described, the following conclusions may be drawn : — }ranchester Memoirs, Vol. Iv. (191 1 j, No. 10. 9 (i) Metaboric acid is probably a definite compound, or hydrate of boric anhydride. (2) No clear evidence can be found for the existence of any acid containing less water than metaboric acid. (3) Only orthoboric acid can exist in solution, under which conditions it is present in simple molecules. (4) Metaboric acid cannot be regarded as an equi- molecular mixture of orthoboric acid and boric anhydride. (5) Fused mixtures of orthoboric acid and boric anhydride, in which the molecular ratio of the latter to the former compound exceeds 41, can exist in a vitreous metastable and a crystalline stable form. Boron and aluminium being members of the same group of elements, analogies may be expected between them, and, as in the case of the latter element, a very complicated series of hydrated oxides are believed to exist, the same may be true for boron. This view would help to explain many of the experiments described in this paper, the ortho variety being the only definite acid of boron. The University, Manchester. Man Chester Memoirs, Vol. Iv. (191 1), A^^. 11. XI. Studies in the Morphogenesis of certain Pelecypoda. (2) The Ancestry of Trigonia gibbosa. By Margaret Collev March, B.Sc. (Comviunicated by Dr. George Hickling.) Read February jfh, rgii. Received for publication Marcli jik, igii. The Trigoniffi were subdivided by Lycett into eight groups. This classification was made in 1875, ^"^ was, therefore, based on adult shell characters. The subsequent work of Hyatt, Beecher, and Jackson has shown that the characters of true taxonomic value are nepionic. In trying to construct a classi ication of the Trigoniae, there- fore, the characters to note are those of the early shell. The classification of other fossil Pelecypoda has been worked out along two lines, either on form or shell structure. Alteration in form was used by Jackson in his classification of the Aviculida^. In this case the group showed progressive adaptation to the sedentary habit, so the modification in form was biological. The Trigoniae, however, show no such progressive adaptation, — their modification, therefore, is of a purely individual character and dependent on environment. Such purely cecological variation is of no taxonomic value. Alteration in teeth structure, muscle scars, and pallial line has been used as the basis for a general classification. Variation in teeth can be used in the classification of the Unionidge, which show perfectly graded series from April 20th, igii. 2 March, Morphogenesis of certain Pelecypoda. strongly toothed to totally edentulous forms. So far as has yet been worked out the Trigoniae show a marked uniformity in teeth, muscle scars, and pallial line, the most marked variation being the development of ligamental pits in the Scabrae (Lycett). Some other method of classification must, therefore, be used in their case. This is obviously the development of their ornament. Development of Coficentric Trigonid Ornament. The Trigoniai are definitely known from the Trias, so that it might be inferred that in Triassic times the ornament would not have diverged from the simplest {i.e., concentric) type. But this is not the case. Three types of ornament are known in Triassic times. {a) Pure concentric. Myophoria curvirostris. {b) Concentric, showing the introduction of tuber- culate radial on the posterior part of the area. M. lineata. {Figs. I. and II. of Plate) [c) Tuberculate radial. T. harpa. Since no intermediate types are known, it seems probable that the Trigonise are either polygenetic, or that their origin is so far pre-Triassic as to allow of the development of two of the three m.ain types, a«nd extinction of the intermediate forms of ornament by Triassic times. However that may be, it should be possible to trace out the subsequent development of these types of orna- ment, and the first to be followed is naturally the con- centric. In the Middle Lias occurs T. lingonensis. This is purely concentric in ornament on both area and flank. Its later stages, however, tend to become smooth. Its importance, therefore, does not lie in its being in the main MancJiestcr Memoirs, Vol. Iv. (191 1), No. II. 3 line of descent, but in proving the continuance of this type of ornament in Liassic times. In the Inferior Oolite occur two types with concentri- cally marked umbones, showing them to be derived from the pure concentric M. curvirostris type. {a) T. v-costata. In these the area is pure con- centric, as is the flank in nepionic stages. In later stages, however, these concentric flank markings break up near the marginal carina into alternating tubercles which rejoin diagonally, forming a marked V in that region of the shell. For the formation of at least one V one pair of anterior costre unite to join one posterior limb. This is important, as it is a constant character throughout all forms which have V's or V-like undulations, and it is retained after the disappearance of this undulation. {b) T. costatula. Here the ornament is purely con- centric until late ephebic and gerontic stages where the flank markings begin to break up near the marginal carina into alternating tubercles. Of these two types, T. v-costata seems to have reached a definitely phylephebic stage of ornament, and T. costatula to be still in a phylo-nepionic state. The Great Oolite shows the continuation of T. costatula in T. painii. Here the nepionic stages are M. cjirvirostris and T. costatula. The ephebic show the introduction of further alternate pustulation, and the elongation of these pustules to form marked undulations near the marginal carina, though not the formation of a V as in T. v-costata. Here also occurs T. clytia which is a descendant of T. v-costata, differing from it in the regular junction of two anterior costse to one V after nepionic stages. In the Forest Marble is found T. undulata which appears to be a further evolution of T. painii. In the 4 March, ISIorphogcuesis of certain PcJccvpoda. Ccrnbrash is T. detrita which is a later variety of T. v-costata and T. nndulata again, which also appears in the Corallian with T. gecgrapJiica, a closely allied form to T. costntitla. So far as I know no Trigonine of this type occur either in the Oxfordian or Kimmeridgian clays. But, as these deposits were laid down under very similar physical conditions, and as these forms occur before, between and after them, it appears quite legitimate to assume that the conditions under which these deposits were formed were unsuited to these particular Trigoniae. In the Portlandian times these forms with concen- trically marked umbones re-appear and show a rapid development of ornament. The simplest type is T. Damoniana. Here it is neces- sary to point out that two very distinct types are described under the name " damoniana " in Lycett's monograph from types both in Jermyn Street and in South Kensington. In both the area is concentrically marked at the umbo. These forms tend to lose the ornament on their areas in ephebic stages. The flank ornament passes through the curvirostris and costatula types during nepionic stages. When adult the markings consist of concentric costations which reach about half way across the valve, and then break up into the usual alternate pustulations, with, at least in one place, one pair of anterior costse to one posterior row of tubercles. This marks the former existence of the undulation, though it is no longer visible. Its loss may, I think, be attributed to two causes. {a) The greater isolation of the tubercles, which thus tend to lose their diagonal connection. ib) The loss of ornament near the marginal carina, which leaves a clear space where the undula- tion should be. Manchester Memoirs, Vol. Iv. {\^\i), No. W,. 5 The pustules in one type {T. Danioniana a) are small. In T. Damoniana |3 they are large. The typical T.gibbosa of Lycett has reached a slightly further stage in the development of ornament than T. Damoniana o. Its carinal space is larger and better defined, and its costations are further broken up. Some Gibbos?e of Lycett exhibit total loss of costations, and some total loss of ornament. These may be counted as T. gibbosa /3 and 7, or possibly as gerontic stages of T. gibbosa a. The pustulations of T. gibbosa are larger than those of 7". Damonia)ia a. The ontogeny of T. gibbosa is excellently shown by young and adult specimens from a block of Portland stone in the Manchester Museum. Here the youngest shows a pure RL cnrvirostris type, the next a T. costatula stage and a later stage giving the introduction of an undulate type. These stages are again reproduced in well-preserved adults from the same block. {Figs. IV. to VIII. of Plate) T. Damoniana (5, as figured by Lycett in his mono- graph, appears to correspond with T. gibbosa j3, that is to say, its ephebic ornament is purely tubercular, the T. gibbosa a and T. Davioniana a types being lost after neanic stages. (Fig. IX. of Plate.) T. tenuitexta appears to be a further stage of T. Da- nioniana a, as its tuberculations are small, and further developed than in that form. This typeof umbonal marking is seen in the Cretaceous of India and South Africa in the forms described by Dr. Kitchin. Here, however, the flank markings are further modified by their junction into a V which, much as in Gonioniya, occupies the whole flank. 6 March, j\Iorphogenesis of certain Pelecypoda. Classification as based on Ornament. The forms here described fall under Lycett's classifica- tion into two groups, {a) The Undulatse, comprising the Inferior Oolite to Corallian forms. {b) The Gibbos^e, a sub-group of the Glabra?, in- cluding the Portlandian forms. [Bigot.] It is, I think, permissible to class these two together in one great sub-division, the Undulatae. The more usual ancestry for the Gibbosas is to describe them as degenerate Clavellates. The reasons given for doing this are : — (i) Both Clavellates and Gibbosai have concentrically marked areas. (2) The Clavellate umbones are concentrically marked, the Gibbosse type being derived from the Clavellate by loss of the clavellations. (3) The ancestry of the GibbosiK is unknown, and, although the umbones resemble M. ciitvirostris^ yet it is impossible to get a Triassic type in the Portlandian without any intervening links. Against this theory and for the junction of Undulat^u [Lye] and Gibbosje may be said, (i) That there is a fairly complete ancestry bridging over the gap between Triassic and Portlandian forms. (2) That the Undulatae agree with the Gibbosae in umbonal markings in both flank and area. (3) That the Clavellate umbonal flank markings, as I hope to show later, are not concentric. Manchester Memoirs, Vol. Iv. (1911), T^o. H. 7 Table showinc; the positions of the auove-mentioneu Trigonue. RECENT MIOCENE T. pectinata T. aciitLCostata EOCENE T. subiindiilata CRETACKOUS i PORTLAND T. tenuitexta T. Damoinaiia /i . 1 ' T. Damomana u — T. gid/^osa KIM.MERIDUE CORALLIAN 1 T. geogra/>/iiea\ — 7] rindulata OXFORJMAN CORNBRASH 1 — -Z! iiiidiilata T. detrita ' 1 FOREST MARBLE — T. undiilata 1 GT. OOLITE T. clyiia — T. paijiii ^^' INF. OOLITE T v-costata — T. cosUiiula T. dcnticulata LIAS T. lingoneiisis RHi^TIC M. emnirichi TRIAS J/, ciirvi rosiris M. i 1 'i/waia PRETRIAS Pure concentric type 8 March, Morphogenesis of certain Pclecypoda. Affinities of the UndnlatcB \^— Undulated {Lye.) and Gibbosce, Lyc\ The closest connection of the Undulatie appears to be with the Costatit [Lycett]. It has been said that no Costate Trigonia has ever shown the faintest trace of concentric ornament on the area. There is, however, in the Manchester Mnseum a T. denticnlata [Inf. Oo.] with pustulations on the marginal carina which agree in position and number with the ends of the flank costai. Similarly arranged tubercles occur on the inner carina, and joining these two are regularly arranged rows of tubercles. A very young specimen from the Bradford clay, possibly T. detiticniata, hints at the same arrange- ment. From the Rluctic, of Bristol, comes iMyophoria eninnichi, which has purely concentric flank markings and predominant radial markings on the area with a trace of concentric. This can only be seen in a few specimens, and even then with difficulty, as they are not well preserved. In the l^rias occms M. lineata {Fig. II. oi Plate), which, as described before, has pure concentric flank markings and predominant concentric markings on the area, showing the introduction of radial near the inner carina. This traces the costate type of ornament back into Triassic times. Its later development takes place in the Tertiary epoch. The £'^f^?/^ Australasian form, T.subnn- dnlata, shows pure concentric marking on the flank, except close to the marginal carina, where it becomes interrupted, showing the introduction of radial ornament. The Miocene and recent Trigoniae show tuberculate radial ornament over the whole flank, except for a small space below the umbo, near to the anterior edge of the shell. Here occur concentric lines, which at the back, meet JManchestcr Memoirs, Vol. Iv. (191 1), No. 11. 9 the radial ornament, running up to the umbo. The length of these concentric lines is gradually reduced by the in- troduction of radials. Fig. I. Diagram illustrating the umbonal and flank ornament of Recent and Miocene Trigonias. GG = a growth line. This, then, gives the history of costate ornament from early Triassic or pre-Triassic times to recent ; and shows the close connection between it and the Undulate types. General Considerations on Ornament. Beecher has shown that ornament is due to special body activity. As it is the mantle edge which secretes the shell in the Pelecypoda, the ornament must be due to extra activity of the mantle edge, as a whole, at intervals of time. Possibly these time intervals coincide with the variation of the seasons, the ornament being developed in summer when the body activity as a whole is aug- mented. The simplest kind of ornament will then be the purely concentric. {Fig. 3 A.) The next stage to be developed will be that due to a mantle edge which is especially active at definite points. That is to say, the ornamentation will be still concentric, but will also be tubercular. As shown by Beecher tubercles or spines are due to the intersection of two lines of ornament, and these 10 March, Morphogenesis of cerfaiii Pelecypoda. Fig. 2. Diagram illustrating the origin of the undulate tvpe cf diagonal ornament. XXX growth lines across ib.e diagonal ornament. 1, 3, 5. 7 radii. m\ ^ -Pig- 3- - - - - Growth lines. Diagrams illustrating the development of ornament. A. Concentric, due to intermittent activity of the whole mantle edge. B. Tuberculate concentric due to intermittent activit)- of the whole mantle edge, augmented at certain spots. C. Tuberculate due to intermittent activity of definite parts of the mantle. D. Tuberculate radial due to continuous activity of the mantle at definite points, and augmented intermittently. E. Radial, due to continuous activity of the mantle at definite points. F. Tuberculate diagonal due to waves of activity passing round the mantle, and intermittently augmented. G. Diagonal, due to waves of activity passing round the mantle. H. Double diagonal, due to converging waves of activity, starting from opposite ends of the mantle. Manc/iesier Memoirs, Vol. iv. (191 1), Auh II. 11 tubercles will show the introduction of the radial element. This stage might be called tubercidate concentric. {Fig. 3 B.) The development of these tubercles is due to the suppression of the concentric ornament along radial lines. The suppression occurs along each radius and may affect every concentric ridge, or alternate ridges only. In the latter case alternate concentric ridges are suppressed along alternate radial ridges only. In the Trigoniae the latter rule holds, resulting in quincuncially arranged tubercles. After this stage development is possible along two lines, either the concentric lines between the tubercles die out leaving simple pustular ornament, ^purely tubercular stage, or the concentric lines die out, and the specially active spots become continuously active, giving radial lines which show the last stages of the concentric ornament in their pustulations, = ^?/(5^;r«/a/"^ radial stage. These tubercles may die away leaving the purely radial stage. {Fig. 3 C, D, E.) A still further stage of ornament is shown in the Trigonise, where the alternating turbercles join forming diagonals, these may be tiiberculate diagonal, or purely diagonal, or even doubly diagonal ( = V). The develop- ment of ornament then should be from concentric through radial to diagonal. {Fig. 3 F, G, H.) The proof that this is so in the Trigonise, at least, is seen in the Undulata^, where the double diagonal is developed by rejoining of tubercles in ephebic stages of individuals which, in early life, have pure concentric markings. It is also seen in the ontogeny of the modern forms, where the partial concentric umbonal markings are replaced in later stages by tuberculate radial ornament. Their phylogeny, as well as their ontogeny, also bears out this order of evolution of ornament, since the Eocene types 12 March, MorpJwgenesis of certain Pelecypoda. show almost pure concentric flank markings with only a hint of posterior development of radial, and the Miocene, like the recent, lose all trace of concentric markings after nepionic stages. LITERATURE. Bigot. " Contributions a I'etude de la Faune Jurassique de Normandie. Premier Mem. sur les Trigonies." Mem. Soc. Limi. Normand., vol. 17, pp. 261-345. , 1894. Ref. to above. Geol. Mag., vol. 31, p. 230, 1894. Bl.>\ke, J. F., 1880. "On the Portland Rocks of England." Q.J.G S, vol. 36, p. 191, note. Hedley, 1907. "Results of Deep Sea Investigations in the Tasman Sea." Rec. Austral. Mtis., vol. 6. no. 4, 1907. KncHiN, 1903. "Genus Trigonia." Me»i. Geol. Sui-v. India. Pal. I/idica, ser. ix., vol. 3, no, i. ■, 1908. "The Invertebrate Fauna and Palaeontological Relations of the Uitenhage Series." A/in. S. African Mus., vol. 7, pp. 21-250, pis. 2-11. LvcETT, 1875. "Trigoniie." Pal. Soc. Newton, 1903. "On Bornean Jurassic Shells." Proc. Mai. Soc, London^ vol. 5, p. 403. Shattuck, 1903. "The Moll, of the Buda Limestone." U. S. Geol. Si (TV. Stremoukhov, 1898. "Russian Mesoz. Trigonise." Bull. Soc. Imp. Nat. Moscow. Walford, 1885. "On the Stratigraphical Positions of the Trigoniaa of North Oxfordshire." Q.f.G.S., vol. 41,. p. 41. Whitfield & Harvey, 1906. " Remarks on and Descriptions of the Jurassic Fossils of the Black Hills." Bull. Am. Mi/s. N'at. Hist.., vol. 22. Wood, 1899. " Cret. Lamellibranchs." Pal. Soc. Manchester Memoirs, Vol. L V. {lYo. 11> Plate. in. IV VI. \ II. \"iii. IX. Fig-. I. = M. Uiuala flank ( AI . M. ). ,^ II. = J/, liueata area (iM.M..). ,, III. = Cast from impression from the St<:)nesfield slate, laljelled T. Moretoni (M.M.). 1\'. Cast of young T. ^I'hbosa Portland st<:)ne (M. }.!.). A I. .-(Trowth stages of 7. ^il'bosa from Portland stone (M.M.). VII. J VIII. Adult form, labelled 7'. giMosa (M.M.). IX. 7". Dauiouiaua & (M.M.). Manchester Memoirs, Vol. Iv. (191 1), No. \'i. XII. Some Physical Properties of Rubber By Professor ALFRED Schwartz AND Philip Kemp, M.Sc.Tech. Read Novenibei- 3gt}u igio. Received for publication, Fehi-nary 21st, igii. Introduction. The demand for rubber for industrial purposes has led to an enormous increase in the supply of this material within the last {^^ years. The applications of rubber in the arts are based on some one or other of its many physical properties, and it is now beginning to be recog- nised that more reliance can be placed in the indications given by physical tests on rubber as to its suitability for mechanical or electrical work than in those yielded by chemical analysis. The true function of the physical tests in this con- nection would appear to be to deal with effects, while that of the chemical tests would be to determine the causes which produce these effects. Our knowledge of the physical properties of this important material has not kept pace with its output for industrial purposes, and we are indebted mainly to two early members of this society — John Gough and J. P. Joule — for much of our knowledge of its curious pro- perties. Experimenting in 1802 John Gough^ found that: — " By placing a slip of rubber in slight contact with the 1 Me?n. Lit. ^ Phil. Sac. Manchester, 2nd Series, vol, i. May 2nd, igii. 2 Schwartz & Kemp, Physical Properties of Rubber. edges of the lips and then suddenly extending it he experienced a sensation of warmth arising from an augmentation of the temperature of the rubber, and then by allowing the strip to contract again he found that this increase of temperature could be destroyed in an instant." In his next experiment he found that " If one end of a slip of Caoutchouc be fastened to a rod of metal or wood, and a weight be fixed to the other extremity, in order to keep it in a vertical position ; the thong will be found to become shorter with heat and longer with cold." In his third experiment he says, " If a thong of Caoutchouc be stretched, in water warmer than itself, it retains its elasticity unimpaired ; on the contrary, if the experiment be made in water colder than itself, it loses part of its retractile power, being unable to recover its former figure ; but let the thong be placed in hot water, while it remains extended for want of spring, and the heat will immediately make it contract briskly." Joule^ also observed the curious fact that a piece of indiarubber, softened by warmth, may be exposed to the zero of Fahrenheit for an hour or more without losing its pliability, but that a few days' rest at a temperature con- siderably above the freezing point will cause it to become rigid. The remarkable series of experiments carried out by Joule on the thermo-dynamic properties of rubber will be referred to in detail in connection with the authors' experiments on the same subject. Thermo-Dynamic Properties. When a solid body is subjected to a tensile force, certain molecular changes take place, the mechanism of ■^ " Some Thermo-dynamic Properties of Solids."— /%«/. Trans. ^ 1859. Manchester Memoirs, Vol. Iv. (191 1), No. V'lt. 3 which is not yet fully understood. If the body changes shape, a certain disturbance amongst the molecules is inevitable. The molecules probably become re-arranged, and if the tensile force is sufficiently great, certain groups of molecules may be broken up, whilst other groups will only be distorted, coming back to their original position when the stress is removed. Viewed from a rather different standpoint, these molecular changes may be divided into two classes, each producing its own charac- teristic phenomena, viz. : — (a) A displacement of the position of the mole- cular groups relatively to their positions of equilibrium. {b) A change in the dimensions of the inter- molecular spaces. Both of these effects take place simultaneously, and it is necessary to differentiate between them. The first of these, namely — the movement of the molecular groups past one another, is a cause of heating if we regard the effect as being of the nature of internal friction. In the second case, in order to overcome the attraction between the molecules, work has to be expended on them to increase their distance apart ; this absorbs energy and is consequently a source of cooling. When work is performed on a body due to a change of stress, this work must either go towards increasing the potential energy, or the kinetic energy of the body. The kinetic energy of the molecules re-appears as heat, and thus an alteration in the state of strain of a body results in a change in temperature. There is, however, a con- dition under which no thermal change takes place ; this occurs when the whole of the work done goes towards increasing the potential energy of the body. If, during a given change of strain, the increase of potential energy is greater than the work expended on the specimen, then 4 Schwartz & Kemp, Physical Properties of Rubber. the change will be accompanied by a cooling, since the extra energy must be produced at the expense of the kinetic energy of the body ; or, in other words, at the expense of its heat. In order to measure these thermo-dynamic effects quantitatively, it is necessary to know on what physical quantities they depend. The heat energy produced by the relative movement of the molecular groups past one another is proportional to the total work done upon the specimen in extending it, and, if the rate of extension with load is uniform, this is equal to \We, where ( JF) is the weight (added gradually) which is required to produce the extension, and {e) is the longitudinal extension. Chauveau' states that the second kind of internal work (change in the dimensions of the inter-molecular spaces) is simply a function of the distance traversed by the lead, assuming that the changes of volume experienced by the body are proportional to its changes of shape. Work has to be done on the body in order to separate the molecules of which it is composed ; in other words, its potential energy is increased. This is equivalent to saying it is a source of cooling, for it absorbs heat energy and converts it into strain energy or internal potential energy. Experiment shows that, when rubber is subjected to tension, a cooling effect is first produced which decreases in value to zero, ultimately changing to a heating effect as the tension is increased. In compression, however, the inter-molecular spaces are diminished in size, and heating results from this cause as well as from the movement of the molecules past one another ; these two effects are, therefore, additive, both producing heating. * " Sur le mecanisme des phenomenes therniiques lies a la mise en jeu de I'elasticite du Caoutchouc." Paris, 1' Academic des Sciences, Feb., 1899. Manchester Memoirs, Vol. Iv. (191 1), No. \%. 5 It is apparent that if, on the extension of rubber, first one effect and then the other is dominant, the resulting thermal effects will, at some point, undergo a change in sign, and for a certain extension there will be a neutral point or point of inversion where there will be neither heating nor cooling. At this point the heat energy engendered by the motion of the molecular groups relatively to one another, is equal to the potential energy gained on account of the enlargement of the inter- molecular spaces. This point of neutrality, Chauveau states, exists both during extension and retraction, but not at the same tensions. It is important to note that the two effects cannot be detected at the ordinary temperatures of the atmosphere, but are only found at low temperatures. Perhaps this is due to the fact that, at the higher temperatures, the weak type of molecular group breaks up at the first application of stress, or, it is possibly unstable altogether at the ordinary temperatures of the atmosphere. Under these conditions the extensibility of the rubber is much greater than at low temperatures, and it would seem that the positive work is in excess of the negative work done for all loads. As the temperature is lowered, a point is reached at which the two kinds of work done are equal in amount at the commencement of the application of load, and below this point the negative work would predominate initially. The classic experiments of Joule on this subject were conducted at 6"C. and 7'8°C. in the case of unvulcanised and vulcanised rubber respectively, but it does not appear that he took any great care to keep his temperature constant, and it is quite possible that even a small variation in temperature would affect the result, since Joule says, "At temperatui'es a few degrees higher, the 6 Schwartz & Kemp, Physical Properties of Rubber. reverse action with weak tensile forces did not take place, but that there was, on the contrary, a very shght heating effect." Fig. i is a diagram of his apparatus, reproduced from his original papers. The experiments performed by the authors were conducted at the temperature of melting ice, in order to secure the advantages of constancy which can be thus obtained. Fig. I. Joule's Apparatus. The method of measuring the temperature employed by the authors was substantially the same as that used by Joule, namely, by means of a thermo-junction inserted in a longitudinal slit near the middle of the specimen. The differences in detail consisted in the use of a single pair of copper and iron wires in the case of Joule, and ten pairs of copper-eureka junctions used with a sensitive Manchester Memoirs, Vol. Iv. (191 1), A^^. 1*^. 7 XZS Fig. 2. Joule's Results. Rubber -j^" .si]uaie. Not vulcanised. + <»z y ^ y i / \ y^ ^ 0 y o 'o to 30 ■«» Fig. 3. Joule's Results. Vulcanised Rubber. Section |" square. 1,452 grains per foot. 8 Schwartz & Kemp, Physical Properties of Rnbber. moving coil mirror galvanometer in the present instance. T}-pical examples of the results obtained by Joule are shown in Figs. 2 and 3, which are useful as indicating the magnitude of the effects referred to. In the series of tests which were carried out by the authors, the specimens used consisted of 88% Para rubber, the remaining 12% being mineral matter of small extensibility. The test pieces were 4" square in cross- section and about 6" long. The actual value of the length does not affect the result, since the total quantity of heat generated is directly proportional to the length used. The specimen was suspended inside a glass tube, which was surrounded by a vessel containing crushed ice to keep the temperature constant at o^C. Owing to the very slow rate at which rubber conducts heat, it was found advisable to embed the specimen in a block of ice the night before the test, in order to cool it down to freezing point. In addition to this, the two ends of the containing tube were plugged with cotton wool to prevent the ingress of the outside air. Ten longitudinal incisions were made in the specimen at equal distances apart, in each of which was inserted a thermo-junction made of No. 40 S.VV.G. copper and eureka wires soldered together. These ten thermo-junctions were connected in series and across the terminals of a sensitive moving coil mirror galvanometer, the movement of which was aperiodic, due to the gradual rise of temperature experienced by the thermo-junctions. Weights were attached, by means of a cord, to the lower end of the rubber specimen, and the resulting deflection of the galvanometer noted, the specimen being brought back to a condition of no load between each reading. Frequently a minute or so would elapse before the maximum deflection was registered, so that, except in the cases of the smaller differences of temperature, some heat would be lost by MancJicstcr Memoirs, Vol. Iv. (191 1), No. 1*^. radiation and other causes before the galvanometer came to rest. It was found that a deflection of i mm. on the galvanometer scale was produced by a potential difference of 0*024 1 micro- volts at its terminals. The thermo- electric value of copper and eureka being taken as 40 micro-volts per degree Centigrade, it was found that I mm. deflection corresponds to ooooiQi'C. The curve in Fig. 4 is a typical example of the thermal + ooz fj I - 00^ O OS /o /S Fig. 4. effects obtained by the authors, the neutral point, where neither heating nor cooling takes place, occurring at a tension of 19 lbs. per square inch. The other curve in the same figure is obtained by calculations based on Chauveau's hypothesis. The calculations are based upon a length of I cm. Initial volume of i cm. length =0*4 c.c. Specific Heat =0'4i5 (Joule). Specific Gravity =0965 (Joule). lo Schwartz & Kemp, PhyskaL Properties of Rubber. Ergs required to raise i cm. length through i°C. = 0-415 X 0-965 X 0-4x4-2 X 10^ = 6-'Jiy. 10". It is here assumed that the specific heat and specific gravity remain unchanged on the application of tension. The work done in extension is equal to i\We\ where {W) is the tension applied gradually, and {e) is the elongation. This is equal to the work done in dis- placing the molecules relatively to one another, and is a cause of heating. The work done in enlarging the inter- molecular spaces is equal to A L' where {a) is Poisson's ratio, (Z^) the extended length, (Z) the original length, and (/v") a constant. This work increases the potential energy of the body, and is a source of cooling since it absorbs energy. Thus the effects of the two kinds of internal work are in opposition. If, therefore, it is known at what tension neither heating nor cooling occurs, it is possible to determine the numerical value of (AT). This is done by equating the values of the two kinds of molecular work for the given conditions. Therefore h It' e == A ^^3 ■ , at the neutral point. It is now possible to evaluate the above expressions for different tensions, and to calculate the temperature variations due to each particular load. The following table is an example of such a calculation : — Manchester Memoirs, Vol. Iv. (191 1), No. 13. II •0 V > VO vn 0 VO r^ t-- ro ro VO 10 3 u 0 t« H-> — »H -M hH 1— t 0 ^ 0 0 0 0 0 0 0 0 0 0 P p p 0 P 0 P 0 p P an E b b b b b b b b b b S bt— ~ CO 1 1 1 1 1 ! 1 1 1 + ' j: U u IJ 0 '^ 0 •+• 0 t^ 0 Tj- 0 'i- Ti- H u c 0 I— t— 1 1^ t— 1 «-^ 1— 1 <_> 0 0 5 Sii 0 0 0 0 0 0 0 0 0 0 p 0 p p p p 0 0 0 p a^ rt b b b b b b b b b b 1 1 1 1 1 1 1 1 + 0 H . i: J^ |E? 0 0 u 0 0 0 0 0 0 0 •^v 0 0 0 0 0 0 0 0 0 0 0 LT) ro CO <-o CO Cl '^ -t- t^ «-S cs VO 0 0 H- 0 ON vO M M ;^ 1; 3 S 1 1 1 "" ■" " 1 1 1 + tr. 0 ! 1 1 ^ i; X •^% = S- 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 gativ Don reasii Mole aces i fN t^ ro ro 0 CO rO CO r-~ 0 CO CO t- CTn Tf C^ 10 0 10 hH h- 1 (N tN ro -1- -*• 10 JM 0 a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Positive Don Exte in E 0 M 0 10 'O 0 ^ ^ ro I^ N 10 CO C^ .2« 0 On 0 ^ >J-) -+ ^ -f- <^ ro 2 9 M ro iri r^ 0 •^ ro 10 r^ 0^ S '^ P P P p P — ►- M — K S b b b b b b b b b b W" "5.2 pj CN 0 -t 0 r^ vO 10 ro M CO r-» 0 10 10 '^ 1- -1- Sts r* •I p p p 0 p p 0 0 b b b b b b 0 b b b a; OC.Q ^S"^ 10 10 10 u-) 10 r-* ,^ N to r-« 0 rx 10 r~~ 0 M U-) (J ^ hi fM 50 10 vp t^ oc 0 p-i !!i^ Fig. 9. Spread Rubber Tapt, Rested for 3 Years. Tested under Tension of 50 grams. = 167 lbs. per sq. inch. of 100%, the application of heat was found to lead to contraction only. There is evidently, therefore, some critical load up to which the application of heat results in expansion and beyond which contraction occurs. In the discussion following the reading of this paper Professor Gee pointed out that Schumlewitsch* had come to the * Schumlewitsch. " Ueber den Kautschuk," I'/crU/Jalirssch. dcr Natiirforsch. dsell. Zitriclu 1866. Manchester Meuioirs, Vol. Iv. (1911), No. VZ. 19 same conclusion in 1866. A reference to his paper con- firms the authors' results as to the extension and con- traction on heating under tension, and they hope to extend their observations on this subject. The Mechanical Hysteresis of Rubber. If a rubber test piece be subjected to a gradually increasing load to some point below the breaking load of Ftp-. 10. A. Rubber Testintr Machine. the specimen, and on reaching this point the lead be reduced at the same rate to zero, it will be found that the length of the test piece has been increased by a certain amount of sub-permanent set. 20 Schwartz & Kemp, Physical Properties of Rubber. If the relation between load and extension throughout the above cycle of operations be plotted, it will be found that an area is enclosed between the extension curve and the retraction curve which represents the work done in the rubber itself The authors have employed the mechanical hysteresis of rubber, above referred to, as an index to its quality, and have designed a machine in which the relation between the load and extension can be automatically recorded throughout the test. The machine is shown diagram- matically in Fig. lo. The test piece having been secured in the grips, the fixed grip 'A' is mounted on the pins on the bracket *B,' and the movable grip 'C,' which depends from the specimen 'D,' is connected by the hook 'E' to the cord 'F,' which passes round the floating pulley 'G' to the helical spring 'H.' The load is applied and withdrawn by the up and down traverse of the pulley ' G,' which is effected by means of the cord 'J,' attached to a nut 'K,' which is moved along the guide by the screw ' L', actuated by hand at ' M.' The relation between load and extension is charted in the following way : — The grip 'C,'the movement of which represents the extension, is connected to the pencil carrier ' N ' by the thread ' P ' which passes over the pulley ' Q.' The pencil carrier, which moves between the guides 'R,' contains a pulley 'S,' round which the thread 'F' passes to a stop 'T' (which is adjustable as to position), where it is made fast. The movement of the pencil is thereby reduced to one- half of the extension of the specimen. If necessary, this movement may be again reduced by one-half by the in- troduction of a light floating pulley in the thread 'P.' The movements of the pencil carrier are controlled by the counter-weight ' U.' Beneath the pencil carrier, and moving at right angles to it, is a light table ' V,' on which the chart Manchester Memoirs, Vol. /z/. (1911), No. \% 21 paper is fixed ; the movement of this table is directly pro- portional to the load as it is attached to the spring ' H ' by means of the thread ' W.' The movement of the table is controlled by the counter-weight ' X.' Fig. 1 1 shows a reproduction of an actual diagram, Exbension Fig. II. Reproduction of Actual Diagram showing Constaficy of Results obtained with the Hysleresis Machine. Test-pieces cut from 2,500 megohm cable covering, and put through three cycles of extension and retraction. Curves a^, a.,, a^ are made up of four lines, each due to a separate test-piece. Curvesyi,y.,, /s due to a single test-piece cut from the same cable covering as the others, but containing a longitudinal joint. showing the constanc)' of the results obtained with the hysteresis machine. The following laws are deduced from the results obtained with this machine : — 22 Schwartz & Kemp, Physical Properties of Rubber, (i) The load, expressed in pounds per square inch of the original cross-sectional area of the test piece, is constant for a given extension within certain limits. (2) The work done in extension, in retraction, and in the rubber itself, is proportional to the cross- sectional area of the test piece within certain limits. (3) The areas of the hysteresis loops become constant after about the 6th cycle. (4) The increments of extension, obtained on subject- ing the specimen to a series of cycles of extension and retraction with a given maximum extension, follow a logarithmic law with respect to the number of the cycles. In conclusion, the authors wish to express their thanks to the Principal and Committee of the School of Technol- ogy, Manchester, to Messrs. F. Shaw, B.Sc, and J. Davies, for assistance in carrying out the experiments. Manchestey Mefiioirs, Vol. Iv. (1911), No. IIJ. XIII. The Manner of Motion of Water Flowing in a Curved Path. By Prof. A. H. GiBSON, D.Sc i'luz'crsi/v College, Dundee. Received fa)iitary I jlh. igii. Read February jtli, igii. In announcing the results of his classical experiments on " The Two Manners of Motion of Water," before the Royal Institution of Great Britain,* Osborne Reynolds instances " curvature with the velocity greatest on the outside of the curve " as one of the circumstances con- ducive to direct, steady, or stream_-line motion in a stream or jet of water ; and " curvature with the velocity greatest on the inside of the curve " as conducing to sinuous motion or eddy formation. f The experiment on which this con- clusion was based was carried out b}' means of a cylindrical vessel filled with water. This was allowed to come to rest, after which a colour band of aniline dye was intro- duced diametrically across the vessel, and the latter was rotated slowly on its axis. To quote its author : " At first, only the walls of the cylinder move, but the colour band shows that the water gradually takes up the motion, the streak being wound off at the ends into a spiral thread, but otherwise remaining still. When the spirals meet in the middle the whole water is in motion, but the motion is greatest at the outside, and is therefore stable. The vessel is stopped and gradually stops the water, beginning at the outside. If the motion remained steady * Proc. Roy. Institittion of Great Britain, 1S84. Also " Scientific Papers," vol. 2, p. 153. t " Scientific Papers," vol. 2, p. 157. May 4ili, igii. 2 Gibson, Manner of Motion of ]Vater in a Curved Pat Ji. the spirals would unwind and the streak be restored. But the motion being slowest at the outside against the surface, eddies are formed, breaking up the spirals for a certain distance towards the middle, but leaving the middle revolving steadily." * Various phenomena, of common occurrence in hydraulic work seem, however, to be at direct variance with the opinion expressed above. Among these may be instanced the behaviour of water in a free vortex, and at the dis- charge side of a sharp-edged orifice in a thin plate. In a free vortex, produced by the discharge of water through a central hole in the bottom of a circular vessel, the motion is readily shown, by colour bands, to be steady throughout, although here the motion is ever\'where greater at the inside of the curved path of a filament. Again, on the discharge side of a sharp-edged orifice in a thin plate, during the gradual convergence of the stream tubes to the vena-contracta, the filaments, other than the central one, follow curved paths with the pressure gradually increasing, and the velocity diminishing towards the interior of the stream, and therefore as the radius of curvature increases. Yet such motion is essentially steady and non-sinuous. Another somewhat analogous case is found where a steady jet impinges on a solid surface, or where two stead\- jets, moving in the same straight line but in opposite directions, meet. In each case the motion after impact is steady, however high the velocity. Here again, owing to the change in the direction of flow following impact, the outer layers, while this change is being effected, are moving in curved paths with the velocity greatest at the outer (nearer to the centre of curvature) portion of the curv^e. Experiments on the flow of water around bends in piping also show that the velocity is greatest at the inside of * "Scientific Papers," vol. 2, p. 162. MancJiestcr McDioirs, Vol. Iv. (191 1), No. 13. 3 the bend, and indicate further that the loss of energy in the bend itself is no greater, but on the contrary is some- what less, than the loss in the same length of straight pipe.* This indicates that the stability is increased by changing straight line motion into motion in a curved path, with the velocitj' greatest at the inside of the curve. In view of the apparent discrepancy between the conclusions to be drawn from these results, and those commonly accepted, further experiments, somewhat on the lines originally adopted, have been carried out by the author. In the first of these a cylindrical drum, 4 inches in diameter and 12 inches long, is mounted so as to be capable of rotation about a vertical axis fixed centrally in a cylindrical vessel 12 inches in diameter and 12 inches high. The drum being in position the vessel is filled with water. When this has come to rest a colour band is introduced radially across the space between the drum and the vessel, after which the drum is rotated slowly. The colour band shows that the water gradually takes up the motion, the streak being gradually wound into a spiral thread without any trace of eddy formation. When rotation is stopped the water in contact with the drum is brought to rest, and eddies are formed breaking up the spiral for a certain distance towards the outside of the vessel. The phenomena are therefore identical, whether, as in Reynolds' experiment, the outer layers, or, as in the present experiment, the inner layers, are originally rotating the faster. In the second experiment, the same drum was mounted with its axis vertical and central, over an orifice pierced in the bottom of a cylindrical vessel 2 feet in diameter. Water is supplied to the latter through a volute, opening * BrightiiKjre. I'roc. Inst. Civil Eni^hieeis, vol. 169, 1906-7, pt. iii., P- 334. 4 Gibson, IManncr of JSIotion of Water in a Curved Path, out of its side. An approximation to a free vortex is formed by discharge through the central orifice, the velocity increasing as the radius diminishes, and attaining its maximum value within a short distance of the periphery- of the central drum. Aniline dye was introduced at different points in the vessel, and by its behaviour shows : (i) That the motion is unstable around the peripher}' of the outer vessel. (2) That the eddies formed at this periphery die out as the centre is approached, and that the motion, except in the neighbourhood of the inner and outer boundaries, is essentially stable. (3) That the motion is unstable around the periphery of the inner drum, but that this instability is confined to the immediate neigh- bourhood of the peripher}', the eddy formation being confined to a c}-lindncal annulus, whose radial thickness did not in general exceed one-quarter of an inch. The conclusions which would appear to be justified as a result of these experiments, and of those previously mentioned, are (i) that whenever flow takes place past a curved solid surface, whether this is exposed to water on its concave or its convex side, the motion, except for the slowest velocities, is unstable ; and (2) that in the fluid itself curvature with the velocit}' greatest on the viside of the path tends to stability, while curvature with the velocity greatest at the outside of the path tends to instability. The fact that in the original experiment the eddy formation noted at the periphery of the containing vessel when the latter was stopped, did not extend throughout the whole mass of fluid, is doubtless due to the extremely low velocities obtaining near the centre of the fluid. However inherently unstable the type of motion may be, a certain critical velocity is necessary in order that this may be manifested, and under the conditions of the experiment, the actual velocity was extremely small. Manchester Memoirs, Vol. Iv. (191 1), No. 13. 5 Another fact which the experiments appear to indicate, is that the tendency to eddy formation in the relative motion of a fluid and a soh'd surface is greater, for a given relative motion, when the fluid as a whole is moving past a stationary surface, than Vv'hen the surface is moving through still fluid. This receives indirect confirmation from experiments by Stanton, Beaufoy, Froude, Dubuat, and Morin, on the resistance of plane surfaces when moving through still water, or when held stationary in a moving stream. The results indicate that for a given relative velocity of plane and water, the resistance is greater in the latter case. A possible explanation of this would appear to lie in the fact that in the former case, i.e., with a moving plate in still water, the fluid, except in the immediate vicinity of the moving surface, is in a stable condition, and any eddy projected from the neighbourhood of the surface will be dampfed with a minimum disturbance of the surrounding fluid. On the other hand, with a body of fluid in motion, even if the motion remote from the centre of disturbance is stable, the balance of stability is less than in the former case, and any slight disturbance will have more widely reaching effects, and will lead to an increased loss of energy. Manchester Memoirs, Vo/. Iv. (191 1), No. 14. XIV. On the Periodic Times of Saturn's Rings. By Henry Wilde, D.Sc, D.C.L., F.R.S. Ruei-c'cd and Read .Ipril jj;f/i. rgj i . In my paper on the " Origin of Cometary Bodies and Saturn's Rings," read before the Society in October last,* a new determination was made of the periodic times of the rings, based on the commonly accepted distance of Mimas, y^G Saturnian units. This element of the orbit was derived from observations made by Herschel and subsequently adopted by all astronomical writers. Recent observations of American astronomers with more powerful telescopes and under more favourable con- ditions, have reduced the distance of Mimas from the planet to 3* 16 units, with the consequent increase in the times of rotation of the rings. The difference between the older and later determina- tions is sufficiently large to induce me to place on record for comparison the results computed from both observa- tions and Kepler's third law, as shown and demonstrated in the following tables : — Distances of Mimas = 3*36 and outer edge of ring A = 2'3. CO yZ^' '• 2"3'' : : 22h. 37'm. ; x= I2h. 48-m. for A. Distances of Mimas =3"36 and inner edge of ring C= i'27. (2) i'i6' : V2f : : 22h. 37''m. : x=^\\. 15'm. for C. Distances of Mimas =3'i6 and outer edge of ring A = 23. (3) 3"i6' : 2-3' ; : 22h. 37-m. : x— i4h. 4-m. for A. Distances of Mimas = 3*16 and inner edge of ring Q= 127 (4) 3-I6'' ; 1-27' : : 22h. 37-m. : ,r=5h. 45'm. for C. * Manchester Memoirs, vol. 55, 1910-II. May 8th, igii. 2 Wilde, Ou tlic Periodic Times of Saturn's Rings. The unit distance, 3"i6, for Mimas necessarily involves the correlative reduction of the distances of the other Saturnian satellites, as now set forth in the tables of these elements published by American astrc^iomers. That Saturn's rings are ejectamenta from the interior of the planet is further evident from the fact that no causal connexion subsists between their times of rotation and that of the planet itself, as the inner edge of the ring C has a periodic time of only 5 hours 45 minutes, while the axial rotation of Saturn is 10 hours 13 minutes. The same conclusion may also be drawn with reference to the origin of the two satellites of Mars, as Phobos has a period of only 7 hours 39 minutes, while the axial rotation of the planet is 24 hours ^y minutes. The comparative minuteness of these bodies, which are estimated to be less than 10 miles in diameter, in- dicates them as ejectamenta rather than the successive condensations of a nebular substance surrounding the planet. Saturn's dusky ring and the inner satellite of Mars are the only bodies in the solar system that revolve in a shorter time than their primaries. Mivtclicster McDiflirs, Vol. h. (igw). No. 14. ELEMENTS OF SATURN'S RINGS. Mimas = 3'i6. Distance from centre of Saturn. Time of Revolution. \ Kings. Sal. Units. Miles. h. m. Exterior A. 2-30 84,937 14 4 Breadth 026 9,602 ,, " Mid-breadth ... 2-17 80,138 12 51 Interior A. 2-04 75,337 II 44 Interval 0'07 2,585 ,, ,) Exterior B. 1-97 72,752 I I 8 Breadth 0-47 17.357 ,, ,, Mid-breadth ... 1735 64,073 9 12 Interior B. 1-50 55,395 7 23 Exterior C. 1-50 55,395 7 23 Breadth 0-23 8,493 ,, » Mid-breadth .. i-3«5 51,148 6 33 Interior C. 1-27 46,90 1 5 45 Ball Space 0-27 9,971 1, ,) Sat. Ball roo 36,930 10 13 Mimas 3-i6 116,698 22 ?>7 Alancliestcr Memoirs, Vol. Iv. (191 1), No. 15- XV. Studies in the Morphogenesis of certain Pelecy- poda. (3) The Ornament of Trigonia claveilata and some of its Derivatives. By Margaret Collev March, B.Sc. Read Marclt 21st, igir. Kercived for publication April 4th. igri. The original title of this paper was " The systematic position of Trigo?iia irregularis, Trigonia scarburgensiSy Trigonia dcedaka and Trigonia literata!' It was abandoned for two reasons, yfrj-//;/ because it was too cumbersome, secondly because that part of the paper appeared only at the very end, and in a seemingly incidental manner. I should like to point out that the curious ornament of these forms and their relationships led to the working out of that part of the paper which, in writing, had to come first. The Ornament of T. claveilata. The valves of this species have been described by Lycett* as having "rows of tuberculated costa;, at first oblique, but the later-formed few become more horizontal, or more nearly in accord with the directions of the lines of growth, so that the greater number of rows reach the anterior border in the form of attenuated or sub-tubercu- lated varices ; the posteal extremities of the rows approach the carina at an angle which is greater than a right angle. . .'' The rows of ornament are diagonal, since they cut both radial lines and growth lines. They are formed of *Lycett, 1875. "Trigonia^," Pal. Soc, p. 19. May jotli, igii. 2 March, MorpJwgenesis of certain Pelecypoda. quincuncially arranged tubercles. Indeed this arrange- ment alone gives a semblance of diagonal ornament without any fusion of tubercles, or development of inter- Fig. Ml. J-'ig- "i-l'- Apparent development of diagonal Sliows the apparent development rows owing to (juincuncial of straight lines of ornament arrangement of spots. from the ordinarily arranged tubercles. Fig. 2. Showing the quincuncial airangement of the tubercles of T. claveUata. mediate ridges, as is seen in Fig. \a, where the lines appear to run diagonally, not straight as they do in \b. Manchester Memoirs, Vol. Iv. (191 1), No. 15. 3 The proof of this quincuncial arrangement is obtained by joining up the tubercles next to the marginal carina, then those of the second row, and so on. If, after this has been done, a growth line which cuts a tubercle is traced across the shell, it will be found to cut tubercles on alternate radii only, as in Fig. 2. The diagonals do not form straight lines. The devia- tions from straightness occur in two places. Firstly. The posterior upper and larger part of the diagonal is slightly bent. This is much less clearly marked in late stages. Secondly. Near the anterior edge the lines of ornament bend sharply upward so as to approach a horizontal position. This bend only occurs in those diagonals which reach, or nearly reach, the anterior margin. These curves vary in intensity with the individuals. They are most marked in those specimens which are elongated, and laterally compressed, and have the orna- ment carried right up to the anterior margin. Relation between Growth and Variations in Ornament. The first bend appears to be due to the divergence of the radials. Fig. 3cr represents diagonals of a figure with such radii. As the radials diverge the figure enclosed by them and the concentrics becomes a trapezoid, at the angles of which the tubercles lie, and whose diagonals form the line of ornament. Fig. y gives ABCD and DEFG as such trapezoids. The elongation of the base GF of the figure DEFG forces its diagonal DF out of the line of AD, the diagonal of ABCD. This appears to be the cause of the bending of the upper parts of the diagonals of T. clavellata. 4 March, Morphogenesis of certain Pelecypoda. The absence of this bend in the later-formed Hnes may be due to the fact that the divergence of the radials decreases as full growth is reached. Fig. za. Showins: bendine in diagonals due to divergence of radii. Fig. lb. Showing straight diagonals where the radials are parallel. Showing the cause of bending where the radials diverge. Fig 2>d. Showing bending due to divergence on an actual specimen. Naturally this curve is better developed in elongated forms, as in them divergence is greater, as the difference of length in early and late stages is more marked. Manchester Memoirs, Vol. h. {i<^i\),No. \^. 5 The second and more accentuated bend marks the introduction of that part of the ornament which more nearly approaches the concentric, that is, follows more closely the line of growth. It occurs in that part of the flank in which the growth lines bend sharply upward to run parallel to the anterior edge, and where they are also rapidly closing up. This upward bend causes the concentric ornament and consequently the tubercles in that part of the shell which it affects to be carried upward. So that if A, B, C, D, E & F represent the tubercles of a diagonal row above the bend, and G the tubercle after the beginning of the bend upwards, G will not lie in the straight line AF, but slightly above it in such a way that V \ \ \ > \ > > ^ ^ ^ y y / y ^ y y 7 y / / / / y / / / > Fig. 4- FtS- 5- Showing the development of appa- Showing a double bend on an rently concentric diagonals, elongated 7\ clavellala. owing to uplift. the line will have to bend up to reach it, as in Fig. 2 and also in Fig. 4. The continued uplift may cause the succeeding tubercles of a diagonal row to lie at the same level as, or even above their predecessors, thus forming a horizontal, or even an upcurved line which forms an acute angle with the upper portion. If the uplift is great enough apparent concentricity may be attained by the diagonals. 6 March, Morpkogdnesis of certain Pelecypoda. In laterally wide animals the uplift occurs on the anteriorly-faced part of the flank, where the ornament usually dies away. The diagonals, therefore, do not come into the region of the uplift and so lose this marked bend. It is also absent in any individuals where the orna- ment is not continued to the edge. -5 / Fig. 6. T. navis. Showing straight diagonals. It is clear, therefore, that the deviation from the straight diagonal in the clavellate type of ornament is dependent on the relative growth of the parts of the shell and also on the form of the animal. Sojiie Causes of Variation in Form in Pelecypoda. As has been shown for the British fresh-water UnionidcB^ the form of the individual is exceedingly sensitive to environment. The length of the shell varies with rate of the current and the consistency of the mud in which the animal lives. The width of the animal varies with the composition of that mud. These Unionidce live in very diverse surroundings and are probably a decadent group. These two facts make their range of variation great. Comparing * March, 191 1. " Studies in the Morphogenesis of certain Pelecypoda. (i) Prel. Note on the variation of U. pictoruin, etc." Manchester Memoirs ^ vol. 55, No. 8. Manchester Memo i is, Vol. Iv. (191 1), No. 15. 7 them with the Trigonioe, the range of variation in the latter must be far smaller in Juyassic forms at least, This, however, does not entirely remove these factors from affecting the Trigonia;, though it lessens their apparent effect. One factor is probably removed, and that is current action. Recent Trigonue are found from about 10 to 20 fathoms, a depth at which currents would not be felt. There is no reason to suppose that Jurassic TrigonicB lived in shallower water, so that their elongation cannot be due to current action. It may be due to the consistency of the mud in which they lived. This supposition is supported by the fact that the elongated forms occur in the Oxfordian and Kimmeridgian clays. These were formed under similar conditions from heavy muds, which would tend to retard anterior growth, and accelerate posterior growth, of any animal crawling through them. It is true that T.juddiana is found in the same formation. It occurs, however, locally, and may be due to local con- ditions, as are short forms among otherwise elongated individuals in the UnionidcB. It might, perhaps, even be due to local conditions of food supply, which, in doing away with the necessity for much movement, would reduce the effect of the environment on the shell. A tendency towards the development of an equilateral form would be due to the assumption of some habit, which, more or less, equalized the effect of the environ- ment. Such a form in the modern TrigonicB and in Pecten is associated with the fact that they do not crawl but leap. Some such an equalizing habit must have been adopted by T. dcedalea and its allies. This variation in form and consequent variation in ornament may account for many of the so-called specific 8 March, Morphogenesis of certain Pelecypoda. differences. The variation in ornament, if worked out with its relation to shape, may show relationships of forms whose positions have hitherto been considered doubtful. Extreme Types of Ornament. (li) T. irregularis. This is an elongated Kimmeridgian and Oxfordian form. The extreme deviation of the Fig, ia. Showing the apparent lines of ornament on T. inegtdaris. / /l Fig. ']b. Showing the true lines of ornament on T. iyrcgularis. posterior radials and the well-marked uplift of the anterior concentrics result in the marked bending and even break- ing of tl)e lines of ornament. Manchester Memoirs, Vol. Iv. (191 1), No. 15. 9 ■ This bending or breaking is only seen in the n:iiddle part of the valve, because the extreme deviation of the radials is not felt by the upper diagonals, and the uplift not by the lower. Fig. ya represents a specimen of T. irregularis with its ornament interpreted according to the usual method, and showing at + the introduction of an apparently extra, intercalated row. Fig. jb represents the same specimen, with its tubercles joined up on their right radials. Here no intercalated row is visible, as the radials show that it belongs to the upper part of row/! in Fig. 7^. Fig. 7« row a = row a >) )) )> b = row b 1) )) )) c = row c )) )] »i d = row d j> )) )> e = row e )) ,, )) + = ant. end of row/ >j >» >j /=< ) 1 and ant. post. end of row g \ „ „ row/i >> n >) g= 1 1 and ant. post. end of row h ) ., ., row g ) >) >t 1) h = post. end of row h )) )' )' i = row / )) >) k = row / row k The curious type of ornament is then due to the form, and, if the form is merely ecological, T. irregularis must lose its place as a species and become merely a variety of T. clavellata. A similar reading may be taken for the ornament ot T. scarburgensis, etc. T. dcedalea. This species is characterised by its curious, flattened tall form, and the apparently double set of ornament. lo March, Morphogenesis of certain Pelecypoda. The shape of the animal accentuates the curve of the growth lines. The flatness of the valves brings this curve entirely on to the laterally-faced part of the flank, as there is no anteriorly-faced part for them to run upon. The diagonals get the full benefit of the marked up-curve, Fig. 8a. Showing the efiecl of growth lines similar to those of T. dadalea on diagonals. because they are continued to the anterior edge of the valve. The effect of growth lines, similar to those of T. dcsdalea, on diagonals is seen in Fig. 2>a. The up- curve becomes marked about the middle of the flank. In Mancliesier Meuioirs, Vol. h. {igw), No. 1.%. ii the umbonal region the anterior and posterior parts of the line meet at an acute angle and form a V, the anterior limb of which is approximately concentric. A similar bend Fig. ?>l). SliDwing the apparently double set of ornament in T. dicdalca. Fig. Sc". Showing the cause of tlie development of the second set of ornament on r. dtrdalta. is seen in the enlarged umbo in Fig. %b. This accounts for the curious bent ornament in the upper umbonal region of dcsdalea. About the fourth row down occurs an apparently second set of ornament, running about at right angles to the up-turned anterior limbs of the diagonals. 12 March, MorpJiogenesis of certain Pelecypoda. This, I believe, to be formed from the tubercles of the upper ends of lower diagonals. A possible explanation of the development of a second line ma)' be seen on Fig. 8c-. Here the radials (Ri, Ra, &c.) cut the concentrics (Ci, C2, &c.) at an angle of 45'. The tubercles seen on the figure are quincuncially arranged, as will be seen from the following chart : Ci Co. Ca c, C5 c« Ri 0 + R. + 0 + R3 0 + 0 + R. + 0 + 0 + R5 + 0 + 0 + Re + 0 + 0 R7 + 0 + R8 + 0 + represents a tubercle at the intersection of the concentric and radial. O represents the absence of such a tubercle. A blank indicates that the intersection is not visible on the diagram. On the figure it will be seen that the diagonal distances D, even at so low an angle as 45", are over twice as large as the distances d between the tubercles of succeeding diagonal rows. The result is that on the diagram the apparent lines of ornament run at right angles to the concentric. On the umbo of T. dccdalea the crowding of the growth lines, and the high angle at which the radials and concentrics meet, accentuate this peculiarity and result in the obliteration of the true diagonal lines, and the seeming introduction of a second set of ornament. On this working T. dcedalea has the usual t}-pe of clavellate marking but it is highly modified by the peculiar form of the animal. There seems no need, therefore, to put it into a separate section, as has been done by Lycett. It certainly has no place in the Undiilatce^z.'s, suggested by Manchester Memoirs, Vol. Iv. (191 1), No. 15. 13 Etheridge,* as its umbonal markings are strictly diagonal. It seems to be merely a Cretaceous derivative of T. clavellata. Other Types of Diagonal Ornament. The Scnphoidece [Lycett] are diagonally marked, but differ from the ClavellatcB in not having the ornament continued to where the flank bends round to face anteriorly at least. Consequently, the diagonals form straight lines {Fig. 6). The anteriorly-faced part of the flank is usually marked by transverse bars. These may possibly be due to the coalition of uplifted diagonals, as in the anterior parts of the diagonals of T. clavellata, in which case this group would be derived from the Clavellata proper by loss of the anterior part of the flank ornament. In the Upper Lias of Robin Hood's Bay occurs T. literata, which has been placed by Lycett in the Un- dulates. This position is untenable, because its umbonal markings are diagonal. Its flank markings, consist of well-marked diagonal rows running to about halfway across the flank In front of this are broken, more or less well-accentuated, growth lines which make a seeming V in the central part of the flank. On the anteriorly-faced part of the flank these may become better marked. This type of ornament seems to me to place it in the ScaphoidecB section of the diagonally ornamented Trigonics. T. striata. This species is diagonally ornamented but differs from the others of this type in having spinous serrations instead of tubercles on the diagonal lines. A similar variation is seen in many of the Scabrce. What relationship, if any, there is between the two I do not know, but I hope to do further work on this. * Etheridge, 1881. "On a new species of Trigonia from the Purbeck Beds of the Vale of Wardour." Q.J. G. S., vol. 37, p. 246. Manchester Memoirs, Vol. Iv. (191 1), A^^. 16. XVI. A Plesiosaurian Pectoral Girdle from the Lower Lias. By D. M. S. Watson, M.Sc Read November i^th, igio. Received for puhlicatioii January 24th, igii. The Manchester Museum contains a series of Liassic reptiles, v/hich were collected by the late Charles Moore, of Bath, but never incorporated in his collection ; these reached the Museum through the good offices of Prof Wm. Boyd Davvkins. The most important of them is a specimen of a small plesiosaur from the Lower Lias of the Bath district, most probably from Weston. This specimen shews uncrushed and slightly separated all the bones ot the pectoral girdle, the left humerus and ulna, the right femur, and a long series of dorsal vertebrae. I at first referred it to Plesiosaurus Hawkinsi, a species to which the limb bones and vertebrae bear a very close resemblance. A restoration, made both on paper and with the aid of plasticene models, shewed, however, that the pectoral girdle was of a somewhat different type. I, therefore, made an attempt to develope one of the small fragments of cervical vertebras which remained, and was able to expose the whole of the under surface, which, in the presence of a very marked haemal ridge, differs from the corresponding bone of P. Hatvkinsi. I am not yet able to make a definite identification of the species, but think it is probably Plesiosaurus macrocephaliis. This view is supported by an examination I made recently of the type specimen of P. brachycephaliis in the May igth, igii. 2 Watson, Pectoral Girdle from the Loiver Lias. Bristol Museum, that specimen being, as Lyddeker has pointed out, merely an adult P. viacroccpJialus. Fig. I. Restoration of ihe pectoral girdle ot Plcsiosatirus iiiacroiephalus. Viewed from below x ?.. The coracoids are not restored ; there is a perfect lower surface of the scapula and \ of the clavicular arch are preserved anil are accurately represented in this figure. Notice especially the widely separated anterior ends of the scapula\ L. 9767. Manchester Museum. Description of tlie specimen. Coracoid. Both coracoids are preserved, the right quite perfectly. They are exposed from their ventral surface. Manchester Memoirs, Vol. Iv. (191 1), No. 16. The two coracoids meet in a long median symphysis, but separate from one another both anteriorly and posteriorly, leaving triangular areas, no doubt occupied by cartilage in life. The measurements of the right coracoid are : — Total length ,. Maximum breadth Width of bone at posterior end Length of preglenoid extension Facet for glenoid cavity „ (scapula) 20*3 cm. iO"8 cm. 5-5 cm. 55 cm. 4 cm. Fig. 2. The central and posterior part of the clavicular arch, X I to shew the relation of the interclavicular spine to the clavicules and interclavicular foramina. The upper figure shews the section exposed on the fracture which terminates the spine, in natural position. The bone is remarkable for the breadth and flattened form of the preglenoid extremity and its rather obscure demarcation from the articular facette for the scapula. The bone has the usual thickening between the glenoid cavity and the middle line. One striking character, which it .shares with the majority of lower liassic plesiosaurs, 4 Watson, Pectoral Girdle from the Loiver Lias. is the great narrowness of the posterior part of the coracoid, a condition as different as possible from that which obtains in such genera as Cryptocleidus and its allies. The posterior part of the bone is quite thin and there is no trace of that thickened outer margin which is correlated with the postero-lateral process in such genera as Cryptocleidus and Col}')>ibosaurus. Scapulcr,. Neither scapula is quite complete, but the right lacks only a small part of the inner side of the glenoid end, and has the end of the dorsal ramus still covered by matrix. The left scapula has a complete glenoid end, and perfectly supplements the right. The bone has the usual triradiate form. The lower surface is 9 cm. long, and is gently concave from back to front and from side to side. The glenoid end is slightly wider than the anterior end, both being considerably broader than the middle of the bone ; as the exterior edge is sensibly straight, this implies the development of an inward extension passing under the clavicle. The dorsal ramus is not exposed for its entire length, but as shewn, is very remarkable for its great breadth, which makes the entire bone very deep at the middle of its length. The dorsal ramus is directed almost exactly dorsally : its inner surface is convex across its breadth, a low, and somewhat obscure, ridge running down it, just behind its centre line. The external face of the scapula is very strongly concave, the outer border is a sharp edge from which the upper surface runs in leaving the bone, very thin until it is met by the thin ridge which is the continuation of the dorsal ramus. The clavicular arch lacks a part of the left side and has the right lateral border obscured, but otherwise is excellently shewn. It appears to be quite uncrushed and Manchester Memoirs, Vol.lv. (191 1). No. 16. 5 shews its natural form, a very rare occurrence. The middle part of the under side of the arch forms an essen- tially flat surface varied by a low median ridge which narrows and falls posteriorly into a spine. If this spine is placed horizontally the arch will slope downward in form, a feature of common occurrence in plesiosaurs. From this central comparatively flat region the lateral wings slope rapidly up at an angle of about 130 with the horizontal : at this bend the bone is about "5 cm. thick. The anterior border is as a whole straight, but there is a central bay some 2'5 cm. wide and rather less than i cm. deep. The posterior border of the arch has a median spine which is unfortunately broken off short, but is nearly i cm. thick. The bone on either side of this rod is very thin, and its border runs forwards and then turns gradually out- wards and backwards until it slowly thickens and forms a strong process some 3"5 cm. from the middle line. Out- side this process the border again runs slightly forward and outward until it reaches the outer edge of the bone. The exact shape of this posterior border is quite certain, part of it having been exposed by the splitting of the bone and part developed by myself It is not easy to follow the sutures separating the clavicles from the interclavicle in the anterior part of the arch, but posteriorly their relations are quite clear. The interclavicle runs backward as a spine of triangular section, the point of the triangle being downwards, and the clavicles pass backwards leaving a small foramen on each side of the interclavicular spine until they expand into flanges which are tightly attached to the sides of the interclavicular spine. The mutual relations of the bones of the pectoral girdle are a^follows : — The corocoids meet in the middle 6 Watson, Pectoral Girdle from the Lower Lias. line making at their symphysis a low obtuse ridge on the lower surface, the scapulae are articulated with them so that their lower surface is practically in the same general plane as the coracoid of the same side, the clavicular arch has its lateral wings tightly adpressed to the inner surfaces of the scapulae, the middle of the arch forms a rather broad plate, passing across between the widely-separated anterior ends of the scapula;, and with its posterior border some distance in front of the anterior processes of the coracoids, except, possibly, for the median spine, which may have reached them. The anterior edge of the arch is directed slightly downwards, so that the arch, as a whole, is in a somewhat different plane to the coracoids. The pectoral girdle just described is, on the whole, the most primitive known in the Flesiosauria : it shews that the primitive Sauropterygian had a T-shaped inter- clavicle, with narrow clavicles joining it on both sides. This T-shaped interclavicle seems to shew definitely that the median bone of the Sauropterygian clavicular arch is not a sternal element, for it is obviously similar to the T-shaped interclavicle of the majority of the early reptiles. In correlation with the compression which the anterior border of the girdle has to bear in consequence of the forward thrust of the head of the humerus(see Andrews :io) the clavicular arch is strengthened by the backward growth of the clavicles along the posterior spine of the interclavicle, with which they are strongly united. This enlargement of the clavicles may also be associated with the development of a powerful musculus claviculo-brachialis inserted on to them and the lower and anterior part of the humerus. Such a muscle may have played an important part in the forward motion of the humerus, and have helped to turn it into position for the stroke. The two small foramina bounded by the clavicles and separated by the posterior Manchester Memoirs, Vol. Iv. {\(^\\) No.\i&. 7 spine of the interclavicle can only imply the presence of a pair of small blood vessels, probably supplying muscles, passing upon each side of the interclavicle and persisting even after the backward growth of the clavicles had en- closed them ; in any case they represent the first appearance of the interclavicular foramen, which is found in so many later plesiosaurs. The whole girdle is of interest for its close resemblance to that of Sthenarosaur?cs, where also we find a T-shaped interclavicle, much more modified, however, than in this case, together with widely separated anterior rami of the the scapulre, and a comparatively narrow clavicular arch. These two cases and PIcsiosanrHS ccviybcari are, in fact, the only ones in which the clavicles do not extend back on to the dorsal surface of the coracoids. The furcula of Plesiosaurus arcuaUis, which is generally quoted as shewing a similar condition, is damaged, a similar bone in the British Museum (Natural History) and the conditions in the type specimen of the very closely allied Plesiosaurus megacephahis, shew that there was really a very delicate posterior extension of the clavicles meeting the coracoids. ]\fa)iiJicstcr Ulcj/inhs, Vol. h. (191 1), No. II XVII. The Upper Liassic Reptilia. Part 3. Micmr/eid/^. niacroptcrits (Seeley) and the Limbs of Min-or/cidi/s homnlosj^ojidyhis (Owen). ]^y D. M. S. Watson, M.Sc Reuii Ko'.'eud'er ij^/h. igro. Keceii'cd for ■puhliialion Jaiuiary 24/ Ji, rgii. The Sedgewick Museum at Cambridge only contains one Upper Liassic Plesiosaur, the beautiful skeleton which is the t3'pe of Seeley's Plcsiosaurns inacropteriis. This specimen, which is wonderfully complete, has never been figured, and is so obscured by a very intractable matrix and black paint that little can be made of it. Seeley gives the number of vertebrae as c. 39, d. 24, s. I, cau. 28 ; he includes all the pectorals as dorsals. It is quite impossible to check these numbers with any pretence at accuracy, but the\^ are not far from the truth, and indicate a reptile of the proportions of Mia-oclcidns I/oinalospondj'lus, which has c. 40, p. + d. 5 + 17, s. 3, cau. 20 + . None of the vertebra; are fit for description, but in all regions they appear to be of Microcleidus t}'pe. Of the pectoral girdle only the dorsal rami of the scapulre can be seen ; they project on each side of the pectoral region as narrow bones of oval section pointing slightly outward and backward, they agree exactly with the same parts of the scapula o^ ]\[icrocleidiis Jiomalospon- dylus. Their position shews that the whole girdle is present undisturbed, and that it is of the Microcleidus type, at any rate so far as the scapula; go. May 2gi/i, jgii. 2 Watson, The Upper Liassic Reptilia. Of the pelvic girdle only the ilia are shewn ; they agree closely with those of the type species of Micro- cleidus. The whole skeleton is in fact certainly that of a Fig. I. Right fore paddle of Microcleidiis iiiaaopteriis, dorsal aspect, x \. Drawn from Seeley's type specimen in the Sedge- wick Museum, Cambridge. Microcleidiis and the axial skeleton, and so much of the girdles as can be seen, present no definable differences to the type species of that genus, Owen's P/csiosaurtis homalospondylus. Manchester Memoirs, Vol. Iv. ( 1 9 1 1 ), No. IT. 3 There are, however, certain slight differences of the limbs which suggest that the species is a good one. It is Fii;. 2. Eight fore paddle of Microckidus hoiiiacospoiutyiiis, dorsal aspect, x \. L. 7077. Manchester Museum. very probable that the specimen at York, which is one of Owen's co-types oi P. hoinalospondylns x&-d\\y belongs to M. macroptenis and not to the species to which it was originally referred. In this way the differences between 4 Watson, The Upper Liassk Rcptilia. its pelvic girdle and that of the Manchester specimen, L. 7077, of y]/. Jioiiialospo}idylus may be accounted for. All four limbs of the type specimen of M. macrop- teriis are preserved, and although they are somewhat difficult to make out on account of the imperfect development of the specimen, do give an accurate idea of the structure of the Microcleidus limb. For comparison with them there is only the fore limb of M. Jiouialospotidylns at Manchester, which is described later on in this paper. The right limb of M, iiiacyopterus^ which is the better preserved, is somewhat obscured by matrix, and has a fracture running across the middle of the shaft of the humerus. The dimensions of the humerus are : — length 30 cms., breadth across the head 1 1 cms., across the distal end 18 cms., minimum width of shaft 9 cms.? The head is obscured, the distal end of the bone has the usual flattened form. The anterior border is almost straight, the posterior is strongly concave. The distal end of the bone presents three facets for other bones. Those for the ulna and radius are straight, nearly in the same line, and approximately at right angles to the anterior border of the bone. The third is smaller, and is parallel to the anterior edge of the bone. It lies on the posterior edge. These facets support the following three bones : — 1st. The radius, a flattened bone 9 cms. across proxi- mally, 13 cms. long and 8 cms. wide distally. Its anterior border is nearly straight, but the posterior border is con- cave, so that the minimum width is only 6 cms. 2nd. The ulna, which is a flat bone of irregular shape, which will be best understood from Fig. i. Ma)icJicstcr Memoirs, Vol. Iv. ( 1 9 1 1 ), ^V^;. 11. 5 3rcl. A curious post-axial bone articulating with the humerus and the ulna. This corresponds with a bone figured by Owen in Piesiosaurus riigosiis and by Andrews in Tricleidus. The proximal row of the cari)us is composed of four bones, preaxially, the radiale, a small pentagonal bone with facets for the radius, intermedium and carpalia 2 and 1.'"' The intermedium is a hexagonal bone articulating with the radius and ulna, ulnare, carpalia 3 and 2, and the radiale. The ulnare is also hexagonal, articulating with the ulna, pisiform, a small free space, the 5th metacarpal, by a small facet with the 3rd carpale, and with the inter- medium. The pisiform is a small pentagonal bone articulating with the ulna and the ulnare, and having three free faces which face proximally, postaxially and distall}' ; the first and last are pitted for cartilaginous extensions. The distal row of the carpus consists of the usual three bones. This limb is remarkable for the very close and accu- rate fit of the bones composing it ; they are all polygonal and not mere nodules as are the carpals of Plcsiosaunis sensu strictu. The post-axial bone lying between the humerus and the ulnare is curious, but is probably of no morphological importance. It maybe due to the " sui)ra-abundant bone- producing power " shewn by the very fully ossified carpus. The hind limb is not sufficiently well exposed to be described : it appears to greatly resemble the fore limb, * Tlie numbers applied lo the Ciupalia are tluoughoul of purely de.scri[3- tive sisinilicance. 6 Watsu^, T//C ['/>/>cr Liass/c J^f/>ri//,r. but I could not determine the presence of the super- numerary post-axial bone. The femur is rather more slender than the humerus, its anterior border is slightly concave. The fore limb o^ Microcleidiis Jioinalospondyliis is known from L. 7077 in the Manchester Museum, the specimen of which I have already described the girdles. The humerus is 39 cms. long and 21 cms. across the distal end : the anterior border of the bone is straight, the posterior strongly concave, the distal end shews two facets, inclined to one another at an angle of about 135", there is also a post-axial facet of small size and somewhat rounded. The head is set straight on the shaft, it is a rounded knob 8 cms. in diameter, pitted all over for a cartilaginous coat, with it is confluent the pitted surface of the great tuber- osity, vv'hich has an area of 6 cms. by 4 cms. ; this tuberosity gradually subsides on to the shaft. The radius and ulna resemble exceedingly those of M. macropteriis, they are of equal length, the post-axial supernumerary ossicle of the other species was probably originally present, although it is not preserved. The radiale, intermedium, ulnare, and pisiform are exactly as in M. inacropterus, except that the distal point of the intermedium is truncated and articulates with a small triangular bone completely surrounded by the inter- medium, and the second and third distal carpalia ; this extra bone occurs in no other known Plesiosaur limb, and may be an individual abnormality ; in any case, it may represent one of the centralia which must have occurred in the ancestors of the Plesiosaurs. Another small triangular bone, of which the exact position is unknown, is probably a pre-axial accessory bone similar to that figured by Fraas in the fore limb of jMancJicstcr Memoirs, Vol. Iv. (191 1), No. IT. 7 Plesiosanrns victor loetween the first metacarpal and the first distal carpal. The most marked features of the limb are the extra- ordinary width of the carpus compared with the hand and the close fit of all the constituent bones. Fiq. 3. Fore paddle of P/esiosaiirns niacro- cephalus. x ?.. L. 9766. Manchester Museum. To shew the apparent remains of the skin indicating the former existence of a posterior extension of the fin un- supported by bone. This disproportionate width of the carpus raises the suspicion that the hand had in life a considerable posterior extension supported by non-calcified tissues. The existence of such an expansion will explain the great 8 Watson, The Upper Liassic Rcptilia. massiveness cf the fifth digit, and seems to be supported by a curious specimen at Manchester. This specimen is a sph't slab of hard calcareous shale of light yellow colour, which contains the distal phalanges of a Plesiosaur limb, and the impression of the proximal portion, surrounding this limb in certain areas is a tliin dark brown film, whose distribution is shewn by the black areas of y^?^. 3 ; this film has a curious and distinctive appearance, and is, I think, certainly the preserved skin : on the anterior border it keeps quite near to the bone, but posteriorly it forms a large expansion which, I think, is probably natural, and represents the posterior extension, whose presence was so probable in Microcleidiis. A brown film, similar to that which surrounds this Plesiosaur paddle, also occurs in connection with some Icthyosaur skeletons at Manchester. The hind limb o{ Microckidus Jionialospojidylns is solely represented by the femur, which is present in the Man- chester specimen L. 7077. The femur is a slender bone with concave anterior and posterior edges, its shaft is small and of oval section, the distal end shews two articular facets. The bone is }^6 cms. long and 19 cms. wide distally, the head is nearly hemispherical, being 8 cms. in diameter, and is confluent with the great trochanter, which is of very large size, its proximal termination forming a face 5 cms. square, inclined at 45° to the long axis of the bone. This face and the head of the bone are pitted, and in life must have been covered by the same cartilaginous coat. The great trochanter gradually subsides into the shaft of the bone, which on its lower surface exhibits a triangular raised and roughened area, which marks an im- pprtant muscle attachment. Manchester Memoirs, Vol. Iv. ( 1 9 1 1 ), No. 1 1. 9 The account of the h'mbs given above shews how slight is the difference separating Microcleidus hojiialo- spondylus and M. macrop terns. It would be quite impos- sible to separate them on the evidence presented by any individual bone, but the fortunate occurrence of several good skeletons shews that they are certainly different. The limbs shew an advance on the type most common in the Lower Lias in their much more extensive ossification, and also in the fact that the radius and ulna are of the same length ; in all the species from the Lower Lias the radius is very considerably longer than the ulna {Fig- 3)- Only one Upper Liassic species has yet been described which has limbs at all closely resembling those of our genus : — Plesiosaurus Guilelnii luiperatoris, of which the limbs strikingl}' resemble those of Microcleidus ; I believe the two types to be very closely connected, and shall discuss their relationship in a future paper when I describe the skull o{ Microcleidus. Manchester Mcuioirs, Vol. Iv. (191 1), No. 18. XVIII. Notes on some British Mesozoic Crocodiles By D. M. S. Watson, M.Sc. Read December i^th. igio. Receii'ed for pitblication Janua)-y 2-^th. igii. I. Steneosaurns stepJiani, Hulke. The under surface of the skull was not described by Hulke in his description of this species ; it has recently been further developed, and now shews some interesting features. The basi-occipital shews the usual single condyle for the atlas ; it is unusually short and flattened. The two lateral processes for muscular attachments are small in proportion to the great size of the skull ; they are separated by the pit in which lies the opening of the median eustachian tube. The grooves at the junction of the basi-occipital and basi-sphenoid, which lodged the canals leading from the lateral to the median opening of the eustachian tubes, are well marked. The basi-sphenoid is only exposed on the ventral surface for a short antero-posterior space : it is as usual divided by a median ridge, with a wide flat surface, which separates the grooves leading down and round to the underside of the quadrate, the meaning of which is still obscure. S. stephani is unusual in that these grooves are entirely directed laterally. Very little of the pterygoid remains. Only a small area some 4cms. long behind the posterior nares is repre- sented by actual bone ; but the impression of the right pterygoid and ecto-pterygoid gives a good idea of what May 2gth, igii 2 Watson, Notes on some British Mesozoic Crocodiles. appears to be the real outline of the bones. Their form will be best understood from Figure i. The posterior nares instead of being rounded, as they usually are in typical members of the genus, are bounded anteriorly by the nearly straight posterior borders of the palatines. These form a bracket-shaped line with a notch in the centre. The small scrap of pterygoid remaining shews a median ridge. /'>^'. I. Steneosaunis stephani, Hulke. Sonievshat restored drawing of the under surface of the type skull, x { to show especially the form of the posterior nares and llie area of the pterygoids. On the existing evidence it is impossible to determine whether there was any trace of the shallow pit or depression into which the posterior nares open in typical Steneosaurs and still more markedly in Pelagoscxurus. Manchester Memoirs, Vol. Iv. (191 1), ^0. 18. 3 The surface of the palatines is generally flat, but there is a slight median ridge separating two shallow grooves. The sub-orbital vacuities are short and broad and the ecto-pterygoids very feeble. Steneosanriis stephani comes from the Cornbrash and is hence one of the earlier types of the genus. It is ot interest to compare it with other early species. In his "Notes paleontologiques" Eudes-Delongchamps figures a plaster cast of a skull from the English Corn- brash which he identifies with his 5. Boutilieri. This skull consists almost entirely of rostrum and is hence rather difficult to compare with S. stephani: so far as corresponding portions of the two skulls occur, they agree, and it is probable that they belong to the same species. The Bristol Museum contains another copy of this cast, and I found there a cast of the back of a Steneosaur skull which may belong to it ; it agrees closely with S. stephani, but as there is no real evidence that it belongs to the snout, I think it is preferable to keep the name stephani for the Closworth skull. Compared with typical late members of the genus Steneosani-us stephani approximates to the Mystriosanrns type in its unusually large pterygoids and its relatively small supra-temporal fossae : from this genus, however, which I have studied in a magnificent series of specimens of the species Brongniarti at Manchester, >S". stephani differs in the absence of pre-orbital vacuities, in not having the posterior narial opening pointed in front, and in the much smaller pterygoids. In fact, in the condition of its pterygoids and supra- temporal fossae, it is exactly intermediate between Mystriosanrns and such a species as Steneosanrns Jiebcrti. 4 Watson, Notes o?i some British Mesozoic Crocodiles. It is probable that the reduction of the pterygoids is to be correlated with the enlargement of the temporal muscles implied by the increase in size of the supra- temporal fossae, for this enlargement would imply a reduction of the pterygoidal muscles and hence of the pterygoid and ecto-pterygoid : the fact that this reduction increases regularly as time goes on shews that the Steneosaurs can have given rise to no eu-suchian form, for in all " procoelia " the pterygoidal muscles are greatly developed at the expense of the temporals. 2. MetriorhyncJnis cp. Jiastifer : from tJie Cora/lin?i of Headington. Crocodilian remains other than isolated teeth are so rare in the Corallian that some account of a large part of the rostrum of a MctriorJiynchus from the Corallian, Lower Calcareous Grit, of Quarry Field, Headington, may be of interest. The specimen was obtained by Mr. Manning, and is now in the Manchester Museum, number L. 6459. It consists of a part of the snout including the tip of the frontal and terminated anteriorly by a transverse fracture in front of the nasals. So far as it goes it is quite perfect, being uncrushed. The skull was mutilated before fossilisation, the exposed edges being rounded. I do not consider that this indicates derivation of the specimen from some older bed but merely natural washing about on a beach. The specimen is remarkable for its great solidity, the frontal being some 30mm. in thickness, and the pre-frontal of similar substance. Viewed from above the specimen shews the maxillae meeting one another in the middle line for some 5cms. In this region they form an almost flat dorsal surface from Matichcstcr Memoirs, Vol. Iv. (191 1), No. 18. 5 which the sides fall away leaving a somewhat marked edge. The nasals are large bones which meet in the middle line for 25cms, At the anterior end of the orbits Fig. 2 {a\ Fig. 2 [,b). Fig-. 2. Meirioriiymihus cp. hastifer. F"roni the Corallian ul Headington. Dorsal, right lateral and ventral views of the snout, X \. L. 6459. Manchester Museum. where they are widest they measure lO'Scms. across. In the middle, and posteriorly they are very much swollen, so that the suture uniting them with the maxillae lies in a rectangular groove. 6 Watson, Notes on some British Mesozoic Crocodiles. The frontal is only represented by a small anterior wedge, which lies between the posterior ends of the nasals. The naso-frontal suture is 6cms. long, probably about 8cms. when perfect. Only a small scrap of the right pre- frontal is preserved. When the specimen is viewed laterally the dorsal surface presents a very gentle concave curve. At the anterior end the upper and lower surfaces become nearly parallel. The chief feature shewn in the side view is a deep and very marked rounded groove on the surface of the maxilla and lachrymal. This groove leads into the orbit. It is present in all MetriorJiyncJius skulls that I have examined ; but as these are commonly preserved crushed flat in soft clay, it is not usually well shewn. As seen here it is a groove some 2cm. wide and icm. deep, leading in under the facet for the articulation of the pre-frontal. The lachrymal must be entirely covered by the groove. Leading out of this groove and plunging downwards and forwards into the cavity of the snout is a small foramen about 5mms. in diameter. This is situated in the suture between the nasals and the maxillae, and may conceivably represent the pre-lachrymal foramen of Mystriosaurus, The large and well-marked groove represents a small smooth notch which occurs at the junction of the pre-frontal and lachrymal on the edge of the orbit in Mystriosmirus and Pelagosaurus, and in a much less marked form in Crocodilus and Gavialis. It probably transmits a small nerve to the facial region. On the palatal aspect only the maxillae are preserved, posteriorly, they show depressed rough surfaces to which the palatines were attached. These latter bones extended forward to the level of the anterior end of the third alveolus. In front of this point the palate is divided into Manchester Memoirs, Vol. lv. (191 i), No. 18. 7 three sub-equal divisions by rounded ridges running longitudinally ; the outer grooves lodge the alveoli, of which 10 are visible on the right side, they are very large, averaging 2cms. in diameter. The central division is a deep channel, which is anteriorly divided by a slight rounded median ridge. The specimen described above is obviously a Metno- rhynchus, and in its great solidity and relatively broad snout is only comparable to three described species : — Metriorhynchus brachyrhynchus, Deslongchamps. M. hasti/er, „ M. palpebrosus, Phillips. Comparison with the figures and descriptions of M. brachyrhynchus given by Deslongchamps and Leeds and with the specimens in the British Museum and that at Caen, shew that the specimen under consideration cannot be referred to this species. In M. brachyrhynchus the snout tapers more rapidly, the nasals are narrower anteriorly and broader posteriorly, the distance separating the nasals and pre-maxillae is smaller, and the palate is not so profoundly channelled as in our specimen. On the other hand, the number of teeth may have been similar. The fragment appears to agree with M. palpebrosus in the gradual narrowing of the snout, and in the fact that the nasals never form the widest part in a transverse section of the skull. There are, however, 18 alveoli in M. palpebrosus in a space corresponding to 10 in our specimen, and the palate does not shew the very markedly channelled form which is so characteristic of our fragment. M. hastifer differs from our fragment in the following characters : — 8 Watson, Notes on some British Mesozoic Crocodiles. 1st. The tapering of the snout is even slower than in our specimen. 2nd. The nasals are shorter. 3rd. In advance of the orbit the nasals form the widest part of a transverse section of the face. On the other hand the palates agree exactly. Des- longschamps specially remarks on the pronounced medial channel of the palate. On the whole the English specimen is probably best regarded as representing a well-marked variety of Ji'. Jiastifer. I hesitate in applying a name to this variety on the evidence of the inadequate material before me. It deserves to be noticed that Owen's Steneosatirus temporalis figured in the " British Fossil Reptiles," and said to be from the Bath freestones, is really founded on the type specimen of Phillips' " Steneosaurus palpebrosus " from the Kimmeridge clay of Shotover. Comparison of Owen and Phillips' figures will render this certain, Phillips' name has priority. The fact that in this instance Owen has made an error in the geological age of a specimen throws doubt on the horizon of " Steneosaurus geoffroyi and laticeps " which are figured in the preceding plate as from the Great Oolite. Koken has already commented on their resem- blance to Macrorhynchus, and they may quite easily be of later date. The present whereabouts of the specimens is unknown. Owen's Steneosaurus latifrons, said to be from the Great Oolite of Northamptonshire, is undoubtedly founded on the specimen in the Sharp collection from the Upper Lias. Comparison of Owen's figure with the specimen renders this certain, for some areas which are restored in plaster on the specimen are indicated as being absent Manchester Memoirs, Vol. Iv. (191 1), No. 18. 9 in the figure. It is difficult, allowing for the different class of preservation, to see how Steneosmirus latifrous, Owen, differs from Steneosaurus brevior, Blake. The species is really a Mystriosaurus. 3. MetriorhyncJins hastifer from the Kinimeridge clay of England. The Sedgewick Museum at Cambridge contains the anterior end of the snout of a MetriorliyncJins from the Kimmeridge clay of Ely that undoubtedly belongs to M. hastifer. The specimen is of interest, because it shews the very perfectly preserved anterior nares, which are of the ordinary type. The tip of a tooth is visible in one of the alveoli. It has a crown covered with fine irregular, more or less longitudinal, wavy ribs. It appears to be definitely identical with the tooth figured by Phillips as Steneosaurus longirostris, Cuv. Phillips' specimen consists of the alveolar borders of a large part of the upper jaw, and so far as it goes appears to agree closely with the type specimen of M. hastifer now at Paris. The Oxford University Museum also contains a very characteristic frontal of this species from the Kimmeridge clay of Shotover. 4. "' PetrosHcJiHS lacvidens ''from the Purbeck of Swanage. This species was founded by Owen on a skull and mandible from the Middle Purbeck of Swanage, theo- retically associated together. The skull is exceedingly crushed and somewhat weathered, but with care all the sutures of the upper surface can be made out. They are shewn in Text- figure 3. When this figure is compared with the figure of MacrorhyncJius scJiaumbergensis, given by Koken, no 10 Watson, Notes on some British Mesozoic Crocodiles. differences of generic value are to be seen, and the only character recorded by Owen and Lyddeker which would serve to separate it from that genus is concerned with the position of the posterior nares. In Macrorliynchtis these are placed very far back — nearly as in a modern gharhial ; whereas in Petrosuchus they are said to be in the middle of the skull and to be flanked by a pair of projections. Actual examination of the specimen shews that it is far too badly preserved to justify any such contention ; the Q_^ Fig. 3. Dorsal surface of the type skull of PhoUdosmirtis decipieiis (ohm Petrosuclms laevidens). x ^ to show the sutures between the various bones which are only partly floured by Owen. lower surface is crushed, and it is impossible to dis- tinguish between the matrix and the bone, to which it very tightly adheres. The two projections, which have been supposed to mark the position of the anterior edge of the posterior nares, are really formed by the crushing through of the descending processes of the pre-frontais, which articulate with the anterior ends of the pterygoids. Manchester Mcinoirs, Vol. h. {igw), No. l^. ii Their position favours this suggestion, and they can be exactly paralleled in crushed skulls of Mystriosanrus. There is hence no reason for separating the skull described as Petrosnchus laevidens from Macrorhynchus, which Koken holds to be synonymous with Pholidosaiirus, H. V Meyer, which has priority. All the skulls of PJiolidosaurns have a very elongated rostrum, being of gavialoid proportions. The Petrosuchus skull is damaged anteriorly, so that no direct evidence of its length is possible. The lower jaw, which Owen theoretically associated with the skull, is quite short, and seems to shew that the — o o o o ^rTr^Q-Q-To— Q Fig. 4. I^ower jaw of Pholidosaurus ? decipietts, from tlie ^liddle Purbeck of Swanage. x \. symphysis was short, only some 2 or 3cms. in length. This jaw, in the posterior part not figured by Owen, has an ornament of deep rounded pits like those on a Goniopholis scute. The skull shews only a very faint ornament of irregular shallow grooves, even the frontal not bearing any deep pits. It is, in fact, certain that the skull and lower jaw described as PetrosiicJms laevidens have nothing whatever to do with one another. There is in the Manchester Museum a portion of the right ramus of the lower jaw of a crocodilian from the Middle Purbeck of Swanage which agrees closely with that figured by Koken for Pholidosaurus scliaumbersrensis. The ornament of this 12 Watson, Notes on some British Mesozoic Crocodiles. jaw is similar to that of the PetrosucJms skull, and it appears to correspond in curve. The length preserved is 29cms., of which 27 are tooth-bearing. Of this length I /cms. are included in the symphysis. The splenial comes well into the symphysis. The dental alveoli are small and well separated, the bone between them being roughened. A transverse section across the ramus in the symphysial region is nearly a quadrant of a circle. The discussion just concluded leads to a curious nomenclatural difficulty, which is as follows : — Owen described the genus and species PetrosucJms laevidens on a skull and lower jaw which do not belong to one another ; the skull belongs to v. Meyer's genus, Phoiidosaurus, and as it is described earlier in the text, should strictly be taken as the type of the species, which would then be known as PJiotidosaur^is laevidens (Owen). This name would be misleading, because the skull shews no teeth, and even the alveoli are not exposed. On the whole it seems best to retain the name Petro- suckus laevidens for the mandible, which does not accurately correspond with any known genus and species, and give a new specific name to the skull, under these circumstances I propose that the skull should be known in future as P Jiolidosaurtis decipiens, Watson. Manchester Memoirs, Vol. Iv, (191 1), No. 18. 13 BIBLIOGRAPHY. Dkslongchamps, E. Eudes., 1863-69. "Notes Paleonto- logiques." Caen et Paris. HuLKE, J. W., 1872. Im J. C. Mansel-Pleydell. Proc. Dorset. Nat. Hist. Field Club, vol. i, pp. 28-32, pi. i. KoKEN, E., 1887. Pal. Alhafidl , vol. 3, pt. 5, p. 355. Leeds, H. T., 1908. Q./.G.S., vol. 64, pp. 345-386, figs., pis. xl. and xli. Lyddeker, R., 1888. "Catalogue of the Fossil Reptilia and Amphibia in the British Museum." Part i. Owen, R., 1849-84. "A History of British Fossil Reptiles," vols. 3 and 4. Phillips, J., 1871. "Geology of Oxford and the Valley of the Thames." Manchester Me}noirs, Vol. Iv. (191 1), No, 19. XIX. The Development of the Atomic Theory : — (6) The Reception accorded to the Theory advo- cated by Dalton. By Andrew Norman Meldrum, D.Sc (Conwwmcated by Mr. R. L. Taylor, F.C.S., F.I.C.) Recei'c'ed ]\Iarch 22)uU igrr. Read April 4th, igri. " From the nature of the human mind, time is necessary for the full comprehension and perfection of great ideas." Thus the histor)' of an idea necessarily includes the reception accorded to it on publication, and the steps by which it came to be of influence in the world. Science, considered as an impersonal thing, advances by assimilating new and sound ideas. Yet this process of advancement, as the following paper shows, depends on the temperaments of individual men. The consideration of i)aramount importance in this respect is the fact that these men, according to their outlook on matters of theory, can be divided into two classes. There are (i) the men who are alive to the immense value of theory in science, and (2) the men who would confine science to a collection of facts and laws, as if it were "based entirely upon experi- ment or mathematical deductions from experiment." * At any given time, the direction in which a particular branch of science advances is determined by a few persons only. Consequently, the men who are inimical ^ P. G. Tail, " Recent Advances in Physical Science," p. 10. May 2gth, igii. 2 Meldrum, Development of the Atomic Theory. to theory may exert a harmful effect on science, by despising and rejecting a theory of the utmost importance. The usefulness to science of the atomic theory is so completely established now, that it must seem strange to us to observe the efforts Dalton had to make, in order to arouse attention to the importance of his ideas regarding atoms. For some nine years, (1801-1810), if not longer, he endeavoured to spread abroad his ideas, both b}' private communications and publicly, by his writings and by lectures in various parts of the country. As will be seen, Dalton's speculations had to encounter dangers of two kinds In the first place; not many people gave themselves much concern about the question of the continuity or discontinuity of matter. They were quite content to go on speaking of ''atoms" and "molecules" in a vague, colloquial sense, and Dalton had to induce them, if possible, to use the words as terms of precision. This done, there was always the possibility that they would reject Dalton's idea of an atom as too hypothetical. His physical atomic theory (described in the fourth paper of this series) was devised in the year 1801, from which time onwards he made many attempts to recommend- it to the scientific world. But for years the only avowed adherent which it obtained was William Henry. The question at issue was a fundamental one, and Dalton's finding on it was ultimately triumphant. The theory ex- pressed his conviction that the diffusion of gases is due to physical forces and not to chemical. But the prevailing tendency of the time was to regard diffusion as due to chemical affinity between the gases concerned, and the strength of that tendency was exhibited by the amount of opposition to Dalton's theory. Its opponents included Manchester Memoirs, Vol. Iv. (191 1), No. 19. 3 Thomas Thomson, John Murray, T. C. Hope, John Gough, Humphry Davy, and Claude Louis Berthollet. Dalton's chemical theory was formed by the 6th September, 1803,'^ ^"^ he proceeded forthwith to extend and apply it, and make it known in every direction. His first efforts, naturally, were made at this Society, where, on the 7th October, he read a paper in which the theory was employed in order to explain the absorption of a gas by water. What he endeavoured to do was to establish a connection between the solubility of a gas and its atomic weight. This paper, as published in 1805, comes to an end with a table of atomic weights, of various simple and compound substances, remarkable as the earliest of the kind ever printed. There is no reason to doubt that the paper contained a table of atomic weights when it was read, but Dalton certainly extended the table before going to press. Dalton was eager both to have his ideas put into circulation and to have a resume of them put on record. In London, in the winter of 1803- 1804, he gave a course of lectures at the Royal Institution, i« which he included a brief outline of the theory. He left this for publication in the Journals of the Institution, but, as he ironically remarked afterwards, " he \yas not informed whether that was done."' Humphry Davy was at the Institution at the time, but Dalton did not succeed in arousing in him - A paper of his, read before this .Society on November 12th, 1802, contains a reference to the chemical theory. This is the paper "on the propoition of the several gases, or elastic fluids, constituting the atmosphere." But it was not published till 1S05, and Koscoe and Harden think it was re- written in the meantime, for it includes results, on the combination of nitric oxide and oxygen, which Dalton did not obtain till 4th August, 1803. (Roscoeand Harden, " New View of the Origin of Dalton's Atomic Theory,' p. 35). I cannot myself doubt that this conclusion is the correct one. •' "Xew System of Chemical Philosophy," 1808, Preface. 4 Meldrum, Development of the Atomic Theory. any interest in the theory, much less any enthusiasm for it. In a course of lectures which he gave in Manchester in 1805, he included an account of the theory.^ But it was not taken up there for years, not even by William Henry. There is not the slightest sign that Dalton would not have welcomed workers on the subject. But the atoms were counted an airy or recondite speculation. Dalton's atomic weight data caused no thrill of excitement, aroused no eager curiosity, no consuming wish to join in his work. In North Britain Dalton had a different reception. Early in the year 1807 he gave a course of lectures, twice in Edinburgh and once in Glasgow. In Edinburgh he says " a class of eighty appeared for me in a few days." At the conclusion "several of the gentlemen who had attended the course represented to me that many had been disappointed in not having been informed in time of my intention to deliver a course, and that a number of those who had attended a first course would be disposed to attend a second." ^ This reception afforded Dalton pre- cisely the encouragement of which he stood in need. "On these occasions," he said, " he was honoured with the attention of gentlemen, universally acknowledged to be of the first respectability for their scientific attainments : most of them were pleased to express their desire to see the publication of the doctrine in its present form, as soon as convenient. Upon the author's return to Man- chester he began to prepare for the press."*^ ■* Two unpublished papers, read before the Manchester Society in 1804, probably included accounts of the theory. The titles are respectively " A Review and Illustration of some Principles in Mr. Dalton's course of lectures on Natural Philosophy at the Royal Institution in January, 1S04," and, " On the Elements of Chemical Philosophy." « Angus Smith, " Memoir of Dalton," p. 58. « "New System ol Chemical Philosophy," 1808, Preface. Manchester Mcinoiys, Vol. Iv. (191 1 ), No. IJ). 5 In the " New System of Chemical Philosophy" both the Preface and the Dedication show that Dal ton was immensely grateful for the attention his speculations received in Glasgow and Edinburgh. The dedication runs: — "To the Professors of the Universities and other residents of Edinburgh and Glasgow who gave their attention and encouragement to the Lectures on Heat and Chemical Elements, delivered in those cities in 1807: and to the members of the Literary and Philo- sophical Society of Manchester, who have uniformly promoted his researches." An account of the theory, often referred to in this series of papers, had already appeared. Thomas Thomson had been so much interested and impressed by the doctrine as Dalton explained it to him in 1804, that he became the first convert to it. He showed as much zeal in the cause as its author. With permission he gave a short sketch of it in the next edition of his " System of Chemistry." This was the third edition, published in 1807, of the most successful treatise of the day on chemistry, and it had more influence, directly, in spreading a knowledge of the doctrine than Dalton's own efforts. It made Dalton's theory known to William Hyde Wollaston in London, to Claude Louis Berthollet in France, and to Amadeo Avogadro in Italy. Thomson found another opportunity of expounding the theory in his memoir " On oxalic acid," which appeared in the Philosophical Transactions of the Royal Society of London in 1808. The very next paper in the Transactions is one by Wollaston — on the carbonates and oxalates of potassium — and he, as well as Thomson, advanced his work as exemplifying and justifying Dalton's theory. By these various means, Dalton's and Thomson's books, 6 Meldrum, Development of the Atomic Theory. and Thomson's and Wollaston's memoirs, it became known in Britain and France, in Italy and Sweden. Not only in these ways, but by personal exertions, Thomson and Wollaston sought to advance the theory. In his "History of Chemistry," Thomson gives a narrative of the efforts that had to be made to induce Humphry Davy to take it seriously. Long as the narrative is, it is quoted here almost in full, for it illustrates the fact that in science the spread of new ideas depends as much on personal efforts, springing from genuine conviction, as on printed papers. It would seem that Thomson and Wollaston failed themselves to persuade Davy. Wollaston, however, converted Davies Gilbert, and he, in his turn, succeeded in converting Davy. " Some of our most eminent chemists," says Thomson, " were very hostile to the atomic theory. The most con- spicuous of these was Sir Humphry Davy. In the autumn of 1807 ^ had a long conversation with him at the Royal Institution, but could not convince him that there was any truth in the hypothesis. A few days after I dined with him at the Royal Society Club, at the Crown and Anchor in the Strand. Dr. Wollaston was present at the dinner. After dinner every member of the club left the tavern, except Dr. Wollaston, Mr. Davy, and myself, who staid behind and had tea. We sat about an hour and a half together, and our whole conversation was about the atomic theory. Dr. Wollaston was a convert as well as myself ; and we tried to convince Davy of the inaccuracy of his opinions, but, so far from being convinced, he went away, if possible, more prejudiced against it than ever. Soon after, Davy met Mr. Davis \sic\ Gilbert, the late dis- tinguished president of the Royal Society, and he amused himself with a caricature description of the atomic theory, which he exhibited in so ridiculous a light, that Mr, Gilbert MancJiester Mevioirs, Vol. Iv. (191 1), No. 19. 7 was astonished how any man of sense could be taken in with such a tissue of absurdities. Mr. Gilbert called on Dr. Wollaston (probably to discover what could have induced a man of Dr. WoUaston's sagacity and caution to adopt such opinions), and was not sparing in laying the absurdities of the theory, such as they had been repre- sented to him by Davy, in the broadest point of view. "Dr. Wollaston begged Mr. Gilbert to sit down, and listen to a few facts which he would state to him. He then went over all the principal facts at that time known respecting the salts ; mentioned the alkaline carbonates and bicarbonates, the oxalate, binoxalate, and quadrox- alate of potash, carbonic oxide and carbonic acid, olefiant gas and carburetted hydrogen ; and doubtless many other similar compounds, in which the proportion of one of the constituents increases in a regular ratio. Mr. Gilbert went awa\- a convert to the truth of the atomic theor}- ; and he had the merit of convincing Davy that his former opinions on the subject were wrong." Thomson goes on to say that Dav\- " ever after was a strenuous supporter " of the atomic theory. This puts his support of the theory far beyond its true value. Davy was never enthusiastic about the doctrine of atoms as such, and he much preferred the term " proportion " to "atom." The following passage, published in 181 1, probably represents his mature opinion on the subject : — " it is not, I conceive, on any speculations upon the ultimate particles of matter, that the true theory of ultimate proportions must ultimately rest."'* Dalton himself was far from satisfied with the re- ception accorded to his theor\-. Hope, of Edinburgh, • Thom.son, '' History of Chemistry," %-ol. 2, p. 293. * /'////. Trans.. iSii, Bakerian Lecture, or Davy's Works, vol. 5, p. 326. 8 Meldrum, Development of the Atomic Theory. could not bring himself to accept it.'' It was criticised adversel}' by Dr. Bostock in Nicholson's Jo7irnal, and Dalton, in reply, quoted in support of it analyses by Dr. Bostock. He then remarks : — " A number of such analyses as these would compel Dr. Bostock and others of your chemical readers to examine the theory of chemical combinations which I have offered to them with more attention, than I fear they do. The present state of chemical science imperiously demands it," ^■ In France, also, the theory was coldly received. Berthollet naturally opposed it, for in its general tendency it condemned his attempt to obliterate the distinction between physical and chemical forces, and, in particular, it was contradictory of his doctrine of chemical com- bination in indefinite proportions (see the first paper of this series). He considered Dalton's theory too hypothetical, and his opposition had great influence. Gay-Lussac, who had been his pupil, was unable to "rid himself of preconceptions due to early training." In his famous memoir, on the proportions by volume in which gases combine, he remained an adherent of Berthollet. Gay-Lussac was always timid in matters of theory. Such was his temperament. On one occasion he laid it down that" in natural science, and, above all, in chemistry, generalisation should come after, and not before, a minute knowledge of each fact." " Such a man was not very likely to subscribe to a doctrine like Dalton's, which pj'oviised to transform the whole province of chemistry. Gay-Lussac admitted the facts adduced by Dalton and Thomson and Wollaston, and that was all. Gay-Lussac conceded to Dalton as much as he must, and nothing more. From his own results it seems obvious ■' Roscoe and Harden, op. cit. p. 153. '' " N^icliohon'' s foiirnal. vol 29, p. 150, iSii. ^1 Ann. Clii/n. I'liys.. vol. 11, p, 297, 1S19. Manchester Memoirs, ]\^/. h. {\g\\), No. V^. 9 now that there must be ver>' simple ratios between the volumes occupied by different atoms in the gaseous state. Many writers^- have assumed that Gay-Lussac, in his memoir, defined the relation between his law and the atomic theory, but, as a matter of fact, he ignored it. He did not recognise the theory, and the subject was neglected and came to nothing in France for years. At length, in 1814, Ampere published a memoir/^ of which the fundamental idea is that the molecules of different gases under the same conditions have the same size, so that equal volumes of different gases contain the same number of molecules. In this memoir, the first outcome of the modern atomic theory in France, Dalton is not men- tioned. In Italy Amadeo Avogadro had forestalled Ampere by three years.^* Under the stimulus of Dalton's specula- tions, of which he had learnt through Thomson's " System of Chemistry," ^^ he composed the memoir in which he advanced and maintained his famous hypothesis, that under the same conditions the molecules of different gases occupy the same volume. This hypothesis, involving as it did a distinct departure from Dalton's ideas, became the fundamental dogma of molecular science only after the lapse of fifty years. In Sweden J. J. Berzelius had been occupied for some time in determining the composition of metallic salts, when Wollaston's memoir reached him.^' Forthwith he set ^" See, for instance, Clerk Maxwell, "Theory of Ileal," lotli ed., p. 326. 1' Ann. Ckim., vol. 90, pp. 43-86, 1814. 1* Jour. Phys., vol. 73, pp. 58-76, 181 1. ^* " In what follows, I shall make use of the exposition of Dalton's ideas which Thomson has given us in his ' System of Chemistry,' " /oc. (it., p. 62. i» Phil. Mag., vol. 41, p. 3, 1813. lo Meldrum, Developnieni of the Atomic Theory. himself the task of testincr the validity of Dalton's theory on the grand scale. As he said, " this way of regarding chemical compounds at once throws such a clear light on the doctrine of affinity, that if the hypothesis of Dalton could be proved, it should count as the greatest step that chemistry had made towards its perfection as a science.'"'' As Lord Morley has pointed out, the people who launch great ideas on the world are seldom the people who apply them. Dalton's and Thomson's efforts to make the atomic theory widely known were really far more valuable than the concrete results they obtained by the use of it. Dalton himself was involved by the theory in a " labyrinth of chemical investigation," where he wandered for many years and wasted his energies. It was Berzelius, and no other, who applied it, made it the foundation of accurate chemical analysis, and proved it to be an organon of incomparable power for the advancement of chemistry. 1' Loc. fit. Manchester Memoirs, Vol. h. ( 1 9 1 1 ), No. "It^. XX. The Conditions that the Stresses in a Heavy Body should be purely Elastic Stresses. By R. F. GwvTHER, M.A. Read and received Marcli ftli, igii. Analytical Preface. To avoid breaking the continuity of the argument in the main body of the paper, I prepare for a change from the usual notation by introducing in this preface a modification which I propose to introduce into the treat- ment of the elastic equations for a spherical shell as usually given in text-books. The Elastic Equations for a Spherical Shell. The displacements in the directions r, 6, 0 are generally written u, rj3 and rsin 67. I propose, in the first place, to omit the factor r in the last two cases, and to introduce the factor sin 8 in the second case. By this means sin 6 will also become an obvious factor in other cases, and the remaining functions will be functions of cos d. Following precedent, 1 shall write ;irfor cos y, and for convenience I shall introduce a differential coefficient with regard to x in the second of the dis- placements. Shortly, I shall write the displacements as u, sin d :r-, Sin 0 w. ex May 22?id, igii. 2 GWYTHER, Conditions of Stresses in a Heavy Body. Then, we shall have for the elements of the strain, cu or r\ ex ex" J I / , CV hv\ r \ ex c^ / _ I / c'z/ _ / _ ,iJ0W\ r \lxl<^ ex) ' sin 0 / I lu . liv r \\ - x^ li^ hr sin y / V'v ev eu' sin 0 / I'v _6v _(3«\ r \ ?'r?ix ^x ex/ ' and A = — + ^{ 2n+2X — -{l -X )■-—, + ■::—]. cr r V ex Ixr b

    dr / sin 0 / c^v Iv , hi\ ■ ^ „ 2W3= (^_^+ +_ =2SinO . Bs, r \ ercx ex tx/ whence or ox e(j) The general equations of elastic motion under gravity become cr r Kcx e

    ) / ev\ Manchester Memoirs, Vol. Iv. (191 1), No. *>fy. 3 Limiting ourselves now to the case of equilibrium under circumstances of symmetry about the vertical axis, the equations reduce to (;// + /,) ^ + ^ _ (( I - a- )e.^) = ^ f) .V, cr r ex (;// + «)z— - 2/1 — (^B:i) =A'' (*''■> <>r ex The last equation becomes r S-T,(r7v) + ~(( I - x-)7i>) = 0, cr' o.v- and need not be carried further. The solution of the first two equations is given b)' / , \ \ , ^ f , oivr) (7'\ vr with u + ^-^'^ = :i(A,r'-^^:)K, or \ ' r''+y ' where V stands for a zonal harmonic. We can complete the solution by taking // = S//^,r^, and r' = Se'„F^,. In accordance with the notation introduced in the displacements, it will be convenient to write the elements of the stress P, Q, R, S, Tsinf), and ^/sin«, so that P, Q, R, S, T, and U are functions of cos 9 or x. General Outlines of Argin/ieiit regarding' Stresses and Elastic Stresses. If a heavy bod}-, say a cylinder, stands on a horizontal plane in equilibrium, and is then held in the same orientation by a grip on its upper surface, the supporting plane being 4 GwVTHER, Conditions of Stresses in a Heavy Body. removed, we deduce from statical considerations that the alteration of vertical stress across every horizontal section is equal to the weight of the body. The conse- quences ma)' be that rupture takes place, or that the strains exceed the elastic limit, but if there is justification for believing that the strains are small and within the elastic limit, we proceed to equate the stresses to the corresponding functions of the strain and obtain the dis- placements in the bod}'. If, again, we consider a massive structure built up /;/ situ, the cases may vary greatly from, say, the substance of the Earth to the greater or less structures raised by human hands. The materials may be complex and of very various characteristics. For the purpose of my argu- ment I shall imagine a concrete wall built in courses of equal heights and so constructed as to allow us to assume a complete bond between the courses. The material of each course is initially in a fairly liquid state able to run under hydrostatic pressure. As it sets it develops in some way a capacity to exert other stresses than hydrostatic pressure and finally becomes a solid mass. As the wall is built up additional stresses are caused in each course by the weight of the superincumbent courses. Finally, we have a wall in which the stresses vary periodically (in the Fourier sense). There appears no justification for claiming that the stresses are elastic stresses, or have the character of such stresses. If, however, we could remove the original structural stress in each course from the whole system of stresses, we might fairly assume the character of elastic stresses for the remaining portion of the stress system. Mathematically, this process now suggested is not greatly different from that employed in the first simple MancJiesUr Memoirs, Vol. Iv. {\C)\\\ No.%^. S example. In each case we should deal with the difference of two stress systems. The practical difference is that we cannot handle the massive structure. In the case of the substance of the Earth, there can be no justification for assuming the whole stress system to be elastic, although a part of it may be so treated. General Principles. In text-books on Elasticity and in numerous investi- gations on that subject, elastic equilibrium " under bodily forces " is treated in a method far from satisfactory, except as descriptive of displacements consistent with elastic stress. The method is to assume that the whole stress system is elastic, and to form equations which can to some extent be solved, and to state that difficulty arises in satisfying the surface-conditions. This method hides what may be the real question at issue, and throws upon the surface-conditions difficulties which may have been introduced by the initial hypothesis, because the stress system is not an elastic stress system. I write this paper to propose a different order of treat- ment, in which the solution of the elastic equations may be convenient and desirable, but will not be the prime essential. It will be necessary to show by examples that the method proposed is a feasible one. The method is first to solve formally the statical stress equations " under bodily forces " for a body of the shape under consideration. There will be three equations con- necting the six elements of the stress, and the solution will give the six elements of the stress in terms of the force system and three quantities conditioned by the form of the bounding surfaces. The stresses so found must satisfy such structural conditions as may apply to the case : the 6 GwVTlIER, Conditions of Sticsscs in a Heavy Body. body may yield but it must not collapse or visibly suffer change of shape. A portion of the solution will indicate definite gravitational structural stresses, and a further por- tion will indicate ' complementary ' stresses, conditioned but not determined. Then, as an assumption, these stresses may be equated to the corresponding expressions in terms of strain for the purpose of determining the conditions under which the hypothesis is admissible, if admissible at all, and finally of determining the displacements when the stress is really elastic. If we eliminate the conditioned functions we should obtain the elastic displacement equations. This may be convenient, but is not necessary. The conditions which it is proposed to find are to be obtained by eliminating the components of the displacement in every possible way, or if it is found more convenient in any case, the displacement equations may be solved first, provided it is recognised that the conditions of possibility still require to be investigated. If a body is rectangular, the difficulty of finding a formal solution of the statical equation will be great, but this case offers the best opportunity of estimating the number of conditions. The elements of a stress, generally, are subject to three statical conditions. If the stress is a purely elastic stress its elements are subject to six further differential con- ditions. Hence the assumption that the stress in a heavy body is a purely elastic stress involves a considerable assumption, but allows of estimation by known formulae. Stresses in a Spherical Shell. Taking the polar system of co-ordinates (/', y, ^), I shall write the elements of the stress {P, Q,R, S, 7'sin^, f/sin0), MancJicstcy Memoirs, ]^oI. h. (191 1 ), No. '/JO. 7 and in the resulting equations I .shall replace cosf^ by x. I shall also assume symmetry about the vertical diameter. Then, if the stresses are supposed continuous about tiie point under consideration, we shall have the equations cr dx cr I - X ex r{^+3r-l^+2S-^^..=^0 (i) cr ex I - .V" It is clear that 6" and T do not appear in the first two of these equations, and that we are at liberty to proceed with those two only. To propose that .S" = 0, T—0, may not be unreasonable ; this would require that the tangent to a parallel of latitude at any point in the shell should be a principal axis of the stress quadric at the point, but it is not very material to the procedure at the moment. For the purpose of engineers, and for practical purposes generally, we have to deal with structural rather than molecular forces. I, therefore, multiply each of these equations by /v/r and integrate from r = a at the interior surface of the shell to r=d, at the exterior surface, noting that P = 0, 7'=0, 6^=0 at each such surface. We thus obtain, writing Q for I Ordr, R for I Rrdr, f7 for I Uuir, S for I i)';v/;', and 7' for 1 Trdr, and inte- grating, Q = Ux - -—- + ( I - o)«'^-l-,, \+x I - a:- r, f-r , "^G , w I s I R = f/.v - ( I - x-)^^- - wx + - ( I - ii)w- t.v I + .,v I — .V" (i--v-)r=i{(i-.v-^)6l, (2) ex 8 G^V^'TIIER, Conditions of Stresses in a Heavy Body. where 7i''=-''''^((?^ -/'''), and the .shell is an open shell bounded 3 b)- the cone for which .i=«. The only relations of this character of which I am aware are given in Rankine's Applied AleeJuDiies, but I am not sufficiently versed in the subject to be sure that they originate with his treatment. Rankine's proof offers no difficulty, except in the assessment of his meaning of the phrase " intensity of pressure." If we assume that \Qrdr is the measure of the "intensity of the longitudinal pressure," \Rdr that of "the ring pressure,''and also assume that 6'=(), 5' = 0, 7'=0, we arrive at Rankine's conclusions, which I gather from various publications by Engineering Institutions in Eng- land, Germany, and America, are used in the calculations for the design of domes in concrete as well as for masonr}', although Rankine only contemplated dry masonry con- struction in his book. A general formal solution of the equations (i) may now be obtained. Write I - .v'' /e-= [/x - I - A-)^- -gi, rx -'-il—^ — ^—^ + 1. . (3) ex I - X- Then, by comparison with (2), we must have ("rXdr^O, ]\[(VicJiestcr Mcntoirs, J'o/. h. (191 1), No. 20. 9 Also since 0 and 6^ are both to vanish when ,r = o, X must have the form 1 where // and 7< are functions of r and .r. On substitution in the general equations of ecjuilibrium we obtain the further equations if C U YT ^X. X / -ir T - 1 ?'--— + 2 U= -::-- - ^( A - i ) , cr ix I - .V" whence Fr= j'r{X+ Y)dr, Ur"- = i- / \xdr - --— „ 1 V(A' - Y )dr . . . (4) cx.l I - .r'.' Since C/ must vanish when x = a, we still have to impose a further condition in this last case. Taking ,- ., /"' , it appears to be necessary that I nivdr + — ^ — „ I vYdr shall vanish when .v = t(, or that i,v^~-^~,Y I - x'- shall have a form similar to that of A'. [We are also enabled to complete the set of equations (2) by finding \Prdi\ and Un/r, say /^ and [/. Thus P= - j'r log ?iX+ Y)dr and i?= - fVlog r ^^dr + -^1 / "?■ lotr r{X - Y)dr \ J ex I - X [J ' J lO GWYTHER, Cflfiditions of Stj'esses in a Heavy Body. The equations of condition, of which the importance is wished to be pointed out, may be written cr hx ^^(r'^-v-uy2{i+.)C\ . .- . . (5) where it is more convenient to use the elastic constants cj and a than ;// and ;/, and where (7= — , ,/= 2(1 +0-)//. 2 W From these equaticMis we misjht eh'minate // and v, but the results are very complex. We have already found the mathematical form which 7( and V possess if the equations are consistent, and these values would exclude the gravitational portion of the stress which is given by .V - a Q'=gpf I - X- X - o ■^= -spf-\^^ + Stress ill a Ions:;, Jicavy circnlar cyliiidrical tube, supported horizontally. Take the interior and exterior radii as a and /;, and assume the tube to be so long that the effects of the ends may be neglected, the statical equations to be satisfied are r^~-\-P^^-Q =gii r cos ^ . cr cH r'^+2C^+'^^-gprs\ne (6) dr cU Manchester Memoirs, Vol. Iv. (191 1), No. 30. n 1 he stresses across the sections of the tube incHned y to the vertical must support the weight of the included portion of the tube. The formal solution will therefore be found from P=pd sin y +/^ cos 9 + S/, cos s% , Q^ir ~ + 2/ jysin 9 + (r ^ + 2/+^prjcos(^ + S^,cos.f0 , U= -pd cos y +2 u, sin sd , where / = 0, when r = a, and when r^d, and j pdr= - ^gfj(d'' - d') , a rp„ = rp + 2 j pdr + g(i{^ — d^) , and, in the series of complementary terms, s^, = r^+ 2^/j, or I r^ +p, ) = r~ - (r - 2) ?^s. \ (ir / cr The equations of condition in terms of displacements are now, cr From these, again, the displacements might be elimi- nated. But, if instead, we examine the solution of the displacement equations, namely, / \ CA CM (m + n)r- zn ~-^ ggrco^^i , cr CO I \ ^ A ^10 ■ ,. hn + n)-;— + 2/ir;r-= -gnrsmO, cd cr 12 GwVTHER, Conditions of Stresses in a Heavy Body. where and cii 11 I bv ^ +- + _ _, cr r r cd 02/ Z^ I Cli 2W = ^r- + - ~ ^^ cr r r cB and if we consider separately the terms «„y sin 6 and vjt) cos 6 in // and v respectively, then r-r-^ + n„-Vo = (i - 2(r)(Ar- + B) , dr r^ + v„-u„= - 2(i - (T){Ar' - B) , cr from the displacement equations ; and the conditions are that ?( ^;~ -"V,,-^ u„\= —2(1 + ., Pavonaria and Halipieris) is in question." The specimen that has been sent to me does not belong to the genus Pavonaria^ because there are no spicules in the pinnae, nor can it be placed in the genus Halipteris for the same reason, and also because the auto- zooids are bound together to form pinnae. I cannot agree with Moroff that in a case of this kind the presence or absence of spicules in the pinnae is a matter of no moment. Nutting, referring to the specimens labelled Verrillia blakei in the Stanford University Museum, remarks " these specimens are preserved in glycerin, and the spicules seem to have largely been dissolved " ; but the spicules in the tentacles of Pavonaria finmarchica are r8 — 2-1 mm. in length, and it is difficult to understand Avhy spicules of this size should be dissolved entirely in glycerin. In 1902, Moroff described two new species of Penna- iiilids that were obtained by Dr. Doflein from the coast of California. One of these, to which he gives the name Pavonaria dofleini, was 1250 mm. in length, the other P. calif ornica 700 mm. in length. Jt is very difficult to understand Moroffs reason for including these specimens in the eenus Pavojiaria. Manchester Memoirs, I ^ol. h. ( 1 9 1 1 j, No. %*^. 1 1 Among the characters given by KolHker (8) of the genus Pavonaria are these " Lange, starke Seefedern mit kurzem, dickem Stiele, und dicken, niedrigen Blattern deren Rand nur undeutHch in Kelche geschieden ist." From the figures given the calices are quite clearly differentiated in Moroff's species. " Radiare Kanale fehlen." In P. dofleini, according to Moroff, radial canals are present, but no statement is made as to their position in relation to the dorsal or ventral side of the rachis ; and they are not shown in the figures. " Kalkkorper von typischer Nadelgestalt in der Hauptstammen der Tentakeln." In P. doflemi there are no spicules in the tentacles. Moroff's statement that spicules are abundant in the wall of the pinnae and in the whole stock, however, proves that there is an important difference between his specimens and the specimen from Metlakatla. But for this difference I should be inclined to believe that PavonariV/y/Vr>d' zi/r Nalin'gesc/uchte Osfasietis. Munich, 1910. 2. Gray, J. E. "Catalogue of Sea-pens." London, 1870^ p. 40. 3. " On the genus Osteocella." A/ni. A^at Hist, ser. 4, vol. 9, p. 405, 1872. 4. "Additional Note on Osteocella." Ann. Nat. Hist., ser. 4, vol. 10, p. 76, 1872, and t.c, p. 406. 5. HiCKSON, S. J. " National Antarctic Expedition," Vol. III. Alcyonaria, p. 13, 1907. 6. JuNGERSEN, H. F. E. " Danish Ingolf Expedition," Vol. V. Pennatulida, 1904. 7. KoLLiKER, A. " Icones Histiologicai." Leipzig, 1865. 8. •' Anatomisch-Systematische Beschreibung des Al- cyonarien." Frankfurt, 1872. 9. Marshall, A. M. "Oban Pennatulida." Eirmingham, 1882. 10. MoROFF, Th. "Studien iiber Octocorallien." Zool.JaJirb. Abth. f. System., vol. 17, p. 390, 1902. 11. Moss, E. L. "Description of a Virgularian Actinozoon from Burrard's Inlet." Proc. Zool. Soc., 1873, p. 730. 12. Nutting, C. C. " Alcyonaria of the Californian coast." Froc. U.S. Nat. Mies., vol. 35, p. 704, 1909. 13. Stearns, R. E. C. " Description of a new species of Alcyonoid Polyp {Favonaria blakei), San Francisco." Mining and Scientific Fress, Aug. 9, 1873. 14. "Remarks on a new Alcyonoid Polyp from Burrard's Inlet." Froc. Calif. Acad. Sci., vol. 5, pp. 7-12 (1873). 15- " Description of a new genus and species of Alcyonoid Polyp ( Verrillia blakei).'" Froc. Calif. Acad. Sci, vol. 5, p. 148 (1873). 16. " Verrillia blakei or Halipteris blakei." Amer. Naturalist, vol. 16, p. 55, 1882. Manchester Memoirs, Vol. Iv. (191 1), No. ^4. XXIV. An Account of some Remarkable Steel Crystals, along with some Notes on the Crystalline Structure of Steel. By Ernest F. Lange, M.I.Mech.E., Assoc.M.Inst.C.E., M.I. & S.Inst., F.C.S. Read May glh, igii. Received for publication June 20th, iqii. The natural occurrence of freely developed crystalline forms in steel has been so rarely observed, that, with the kind permission of Messrs. Vickers Ltd., I have pleasure in bringing before your notice the most perfect example of the free development of a large group of steel crystals with which I am acquainted. These crystals were dis- covered by Colonel T. E. Vickers, C.B., who happened to be examining the pipe in a large rising head which had just been removed from a heavy steel propeller-boss casting, and who noticed their presence in the upper part of the cavity. Impressed with the metallurgical import- ance of the find, he had the mass of metal carefully sawn in two, and the hollow portion freed from the surrounding mass, and the cavity thus revealed photographed, as a permanent record of its appearance. This photograph is just half the natural size, and, as you will see from the copy before you, it shows the cavity incrusted all over with " pine-tree " shaped crystals in various stages of development. The vertical crystals have formed with remarkably little interference, some being separate, and in a few cases reaching the remarkable length of 14 or 15 inches. (See Fig. i, Plate /.). August 2 1st, ign 2 Lange, Some Remarkable Steel Crystals. I believe I am right in saying that this photograph is unique of its kind ; I have searched in every Hkely publication for a similar illustration, but in vain ; I have only been able to find an illustration of a single steel crystal, a very fine "pine-tree" specimen, similar to one of the largest in the present case, which belongs to Professor D. Tschernoff, of St. Petersburg, and which was taken from a cavitj^ in the rising head of a i6o ton ingot of soft open-hearth steel. The reason why such freely developed steel crystals have been but seldom noted, in spite of the fact that steel is a crystalline body, is that they can only form under very exceptional circumstances. The fact that they have only been noted in conjunction with large castings or ingots indicates that very slow cooling is necessary to their formation, and the position in which they have been found indicates that they have formed during the slow descent of liquid steel from the upper to the interior portion of a mass of steel during the con- traction caused by the cooling. In fact the formation of the cavity has given room for the free development of the crystals starting from a comparatively few points as may be expected in very slow cooling. The position of the crystals in the rising head, and close, therefore, to the segregated area, would doubtless be reflected in their composition, and this is shown in the present case by the two analyses that Messrs. Vickers Ltd. have supplied me with. The first analysis was made from drillings taken from an actual crystal, and showed the following results : — Ajtalysis of an actual Crystal. Combined Carbon ... ... ... '43 % Silicon Manganese Sulphur Phosphorus ■191 -> •loi „ •098 „ Manchester Memoirs, Vol. Iv. (191 1), No. 34. 3 A second analysis was now taken of the steel at a point about i inch from the cavity. It was not possible to get clean drillings from any point further away from the "pine-tree" crystal area than this owing to the metal having been all machined away close to the cavity. Analysis outside of the " Pine- Tree " Crystal area. Combined Carbon ... ... ... -345 % Silicon ... ... ... ... -16 „ Manganese ... ... ... ... 102,, Sulphur ... ... ... ... -08 ,, Phosphorus ... I have not the composi •076,, ition of the charge from which the propeller-boss casting was made, but am informed that the bulk of the metal in that particular casting would not contain more than "05 to '06 of either sulphur or phosphorus. There has, therefore, been considerable segregation in the area where the " pine-tree " crystal growth has occurred. A description of the external form of these " pine-tree " crystals is not an easy matter. The " pine-tree " crystal form was not produced in the laboratory work of Dr. J. E. Stead and Messrs. Osmond and Cartaud, although the individual component forms were. As early pointed out by Tschernofif, Sorby, Andrews and others, the crystal form of iron is regular. Osmond says that the crystal belonging to Professor Tschernoff resembles a crystal of alum. This description applies equally to those under consideration. Osmond refers to the crystalline structures which characterise iron in industrial products as resembling skeletons of octa- hedrons united along the axis. He further refers to some crystallites of the cubic system obtained from a solution of chrome alum with orthogonal branches and 4 Lange, Some Remarkable Steel Crystals. octahedral envelopes, which he says recall exactly the beautiful steel crystal of Professor Tschernoff. The late Dr. Hermann Wedding also refers to the "skeleton " structure saying that " in commercially pure "iron the crystals show the form of an incomplete regular " octahedron, that is to say, the external form corresponds " to the octahedron, but the mass of the crystal is not filled " up, but is replaced by beams {Balkeii) which run in a " direction parallel to the octahedron axes, and conse- " quently correspond to the position of the belonging cube "faces. Such " beams " have, in the rule, side " beams " " standing at right angles to the main beams, these also " again have often perpendicular beams of the third " degree, so that the whole is only the skeleton of an " octahedron, and has the external form of a pine-tree, or " as the mineralogist would say, receives a knitted or " net-work (gestrkkte) form." Messrs. Vickers Ltd. kindly placed at my disposal for microscopical examination the end portion of one of the shorter crystals. This was cut into two halves longi- tudinally, bisecting two opposite angles. The two cut surfaces of one of these halves were then ground up to an exact right angle with each other, and then polished and etched with picric acid. On examining the section with the unaided eye, a very striking pattern of remarkable geometrical s}'mmetry was revealed, particularly on allowing the light to fall on the section from an angle. This I photographed direct, and then enlarged to twice the linear dimensions. This photo- graph is faithfully reproduced in Fig. 2, Plate II., without the smallest retouching in any way, and speaks for itself as regards the regularity of the pattern. A line corresponding to the main longitudinal axis is plainly seen, and this is intersected at right angles by a series of parallel lines Manchester Memoirs, Vol. h. (191 1), No. %A. 5 coincident with or parallel to the "terraces" on the exterior so plainly to be seen in Plate I. These parallel lines are intersected again at right angles by evenly spaced short lines, which can be clearly counted in the photograph. To the metallographist the photograph suggests the appearance of rectangular lines of lighter coloured ferrite upon a darker pearlite background, but this is not the case. The bulk of the ground, it is true, is pearlite, but the pattern, as shown, is produced by lighter coloured lines of pearlite on the dark ground, apparently brought out by slight overetching. On turning the section so as to allow the light to catch the bright uncoloured ferrite, it will be seen that this has arranged itself with almost as obvious a general symmetry along the boundaries of the network pattern as shown by the photograph. Under a low power of magnification the ferrite appears as discon- nected uneven lines and rectangles, but the pattern made by the ferrite as a whole is, as before said, unmistakeably in perfect agreement and relation with the pattern in the pearlite itself. Under a high power there is little to distinguish the structure, as revealed in so limited a field, from that of an ordinary unannealed but slowly cooled casting. The structure also showed a great deal of the dove- coloured sulphide of manganese, which was not surprising in view of the analysis. This sulphide of manganese mostly occurred, as is commonly the case, in the centre of the ferrite lines and patches. There is not the smallest doubt that the pattern revealed by the etching stands in intimate relationship to, and is indicative of, the interior crystalline structure of the steel "pine-tree " crystal, and affords valuable evidence of crystallization in a regular system. 6 Lange, Some Remarkable Steel Crystals. As remarked at the beginning of this communication, the formation of crystals of iron or steel having truly geometrical boundaries is of rare occurrence. The question might then be asked in what manner is the crystallization of steel revealed in its solidification from the liquid state in the ordinary way, where the mass of the steel prevents the formation of freely developed crystal forms owing to the mutual interference of the crystal growths. Tschernoff assumes that iron solidifies not in approxi- mately parallel layers, but by the growth of " pine-tree " crystals {Revue Universelle, ser. 2, vol. 7, 1 880). I have myself seen the etched surface of the whole longitudinal section of a large steel ingot, the structure of which at some distance suggested the appearance of interlacing branches. However this may be, this tendency is not independent of other physical circumstances, for it has been observed that the interior of " bled " ingots, that is to say, ingots from which the interior has escaped after partial solidifica- tion, is always smooth. We also know that iron or steel, like many other metals, when solidifying in a mould through the walls of which the heat is rapidly conducted away assumes a strongly columnar structure. Many years ago Mliller, in Germany, conducted a series of experiments on steel ingots to determine the stages of the growth of blowholes, and to do this he poured out the interior of partly frozen ingots at various stages of solidification. He invariably found the interior surfaces smooth and without any surface protrusion of crystal growths {Iroti, January 5th and September 14th, 1883). It would appear, therefore, that the solidification of steel in the ordinary way proceeds in smooth parallel layers in spite of a strong columnar structure, or, at all events, the growth of the crystals keeps absolute pace with the solidification of the steel. You will notice this columnar Manchester Memoirs, Vol. Iv. (191 1), No. 24. 7 structure well marked in the ingot section on the table. (See Ftg-. 3, P/aU II.). Professor Howe, in America, tried to obtain side light on this matter by pouring out the interior of freezing ice ingots, but found the walls to be perfectly smooth. He also experimented with blocks of slag in the same way, but again found the sides of the emptied cavity smooth and free from crystalline markings, although the solidified portion had a strongly columnar structure. Referring to the very strongly marked columnar structure of solidified steel at right angles to the cooling surfaces, you will see, in the case of the ingot section shown on the table, that the section is not wholly columnar ; the section is nine inches square and the largest columns about 3^" long, and an area of about 3" square in the centre is confused or granular. The steel has the following analysis : — Combined Carbon ... ... = "16 % Silicon ... ... ... = '046 „ Manganese ... ... ... = "55 Phosphorus ... ... ... = "049 Sulphur ... ... ... = "032 Nickel = 5-35 The composition of this steel indicates a high melting point ; there is, therefore, less direct transition from the liquid to the solid state, and the confused area would represent the disturbance of the sluggish core sinking more or less towards the lower part of the ingot. The segregation in the centre of the section shows that the same is only just clear of the bottom of the pipe, which, as is usual, had formed in the top of the ingot. It is quite obvious that there is a similarity of cause and effect between the phenomena of crystallization as noted in the " pine-tree " crystal growth and that of the 8 LaN(;e, Some Rcuiarkable Steel Crystals. columnar formation. In both cases there is uniformity of orientation along a main long axis. Rhead believes that the difference of conductivity between the solid growth and the liquid mass is responsible for the uni- formity of orientation in the former case, and certainly the chilling effect of the mould produces the same result in the latter case. You will notice that the columnar crystals do not appear to have much cohesion, and, in fact, the surface cracks often observed in rolling or forging ingots usually pass between these crystals. It will be observed that there is no regularity in the size or formation of these columns ; the lateral growths are irregular, so that the columns interrupt each other in their growth at different distances from their main axis, and there is also no relation in the angles of the lateral growths of the neighbouring crystals. In fact, the crystal growths follow the ordinary law of chemical solutions. When a crystal starts from a point it grows in all directions until interfered with by the growth of adjacent crystals. For the same reason, slow cooling results in large crystals, and quick cooling in small crystals. The columnar structure is due to the rapid absorption of heat by the sides of the mould, tending to make the steel crystallise in long prisms at right angles to the surface, although naturally the crystal grains tend to an equiaxed forma- tion. As the walls thicken, and the flow of heat lessens, the prismatic tendency weakens, and there is a sudden change from the prismatic to the equiaxed formation. There is also, as before remarked upon, the interstratal action of the liquid core. These remarks as to the formation of a columnar structure during solidification hold good for any steel casting whether in an iron or a sand mould ; and at all MancJicster Memoirs, Vol. h. (191 1), No. 24. 9 junctions in rectangular forms, the meeting lines of the columnar formation constitute a great weakness to the casting, which is removed by annealing when the casting is reheated through a certain range of temperature, and kept at a certain heat for a certain length of time, accord- ing to the composition of the steel and the nature of the mecham'cal properties required from the material of the casting. The influence of heat treatment upon the crystalline structure of steel was perhaps most generally made known through the researches of Brinell, and the publicity given to his experiments by the exhibit of the Fagersta Com- pany in the Swedish section of the Paris Exhibition of 1900. A copy of Brinell's chart, showing a graphical representation of the changes of fracture and carbon in steel containing 075 per cent, of carbon while heating and cooling, and dated Fagersta, 1898, lies before you. In this chart Brinell shows that however coarsely crystal- line the texture of the steel might be, on heating the same to the temperature which he calls the " moderate hardening heat IF," corresponding to the temperature at which the carbon of the steel suddenly passes from the carbide or cement state into the hardening state, the steel assumes the finest structure that it is capable of receiving. (Stead referring to this particular chart assumes IF to be about /So'-'C). If the steel is heated beyond the temper- ature 11^, the crystals begin to grow and get the coarser the higher the heat attained. The structure can, however, be restored to the desired fineness by allowing the steel to cool below a temperature denoted as the " annealing heat F," and then to be re-heated to W. The annealing heat F denotes the temperature at which the carbon in steel containing hardening carbon has, during cooling as well as heating, the greatest tendency to pass into cement lo Lange, Some Remarkable Steel Crystals. carbon ; this is the temperature of the well-known phenom- enon of recalescence. Brinell does not state the actual temperatures for V and IV in this case, but Howe states in reference to the same that Brinell's temperature V appears to be Arj (690^0.), and his W appears to be Ac2, 3, and therefore to vary with the percentage of carbon as shown in Roberts-Austen's diagram {vide Fifth Report of the Alloys Research Committee, 1899). If steel is heated to a temperature above W, and allowed to cool slowly without work, the crystal grains continue to grow until the temperature V is reached, beyond which there is no further growth. Now the action of forging or rolling strongly opposes crystalli- zation in the case of both iron and steel. Like agitation of salts crystallising from an aqueous solution, it appears to arrest the development of crystalline structure. It follows from this that all forged work should be finished as near to the temperature V as possible, so as to prevent the formation of a coarse structure during subsequent undisturbed cooling, and it also follows from this that all forgings which are not finished at one heat should have their structure refined by re-heating the whole forging to a suitable temperature as a last operation, in order to destroy any coarsely crystalline structure produced in the parts first finished by reason of their proximity to the portion last heated up for finishing. The experiments of Stead and Heyn show that, for breaking up coarsely crystalline structures in very mild steels, the refining temperature should be about 900 'C, or beyond the highest critical point for iron, and an examination of Brinell's later experiments on the heat- treatment of steels of varying carbon contents would appear to make this hold good for carbon steels also, if Manchester Memoirs, Vol. Iv. (191 1), No. 34. 1 1 the best refining temperature is held to be that which produces the best mechanical tests. In the experiments of Osmond and Cartaud, alluded to in the beginning of this paper, the investigators were able to prove that the three modifications of iron* * Adopting the nomenclature of Osmond (vide Traiisfoiiiiations du Fer et du Carbolic dans Ics Fers, les Aciers et les F'ontes blanches ; Baudoin, Paris, 1888), as was done by Sir W. Roberts-Austen in the Fifth Report of the Alloys Research Committee, 1899, to the modificaiions of iron that take place at certain temperature ranges, the term "gamma" iron is applied to iron above its highest critical point, the term "beta" iron to iron between this point and its magnetic change point, and the term "alpha" iron to iron lietween this point and the temperature of recalescence. The points observed on heating, Osmond marked " c " {chauffage), and the points on cooling " r " ( I'efroidisseincnt) . The following figures are recent estimations by Professor Arnold, of Sheffield University (vide Lecture "On a Fourth Recalescence in Steel,'' 1910) :— Critical Points in Cooling Curves. Arg Ar.> Ar, Absolutely pure Iron ... ... 854T. 750°C. None. ■22 % Carbon Steel ... 8i9°C. 764°— 747"C. 696T. •38% 726°C. 696°C. •63% 7io°C. 695"C. A heating curve with '20 carbon steel showed the following ranges : — 718^ — 729'C. Ac^, transformation of pearlite inlo hardenite (cement into hardening carbon). 735^C. End of "alpha" range of temperature. 738" — 753°C. Ac.i, magnetic change point. 756°C. Beginning of "beta" range of temperature. 840°C. INIaximum of Ac;j. S5o°C. Beginning of "gamma" range of temperature. The recalescence data of a pure saturated carbon steel (c.c. = '89%) were determined by Arnold and McWilliam as follows (vide Journal oj Iron and Steel Institute, 1905, II.) : — On heating Ac^, „, «, maximum at 720°C. Range 7io''C. to 730°C. On cooling Ar^, .^, 3, maximum at 675°C. Range 69o"C. to 66o°C. Acj, Ar^ have to do with the carbon change points, Ac.^, Ar., and Acj, Ar. with the iron change points, but, as seen above, the carbon is the dominating influence, and with increasing carbon contents all these change points gradually merge into the one corresponding to the carbon change point only. 12 Lange, Some Remarkable Sled Crystals. crystallised in the regular system. They reduced ferric chloride in a current of hydrogen at temperatures corre- sponding to the different allotropic forms, and then examined under the microscope the crystals thus obtained. The results showed that " gamma "-iron occurs in all combinations of the cube with the octahedron, and that "beta"- and " alpha "-iron crj^stallise in cubes, and are isomorphous. From what has already been said as to the formation of the crystalline structure in solidifying steel under mutual interference of the crystal growths, we shall be prepared to find, on examining a polished and etched section of normally cooled mild steel under the microscope, granules possessing definite boundaries and without definite geometrical form. We do, in fact, find that the structure of such steel reveals a pattern of irregular polyhedra. These polyhedrons are, however, differently affected by the acid and reflect the Hght differently, thus showing that they each possess a different orientation, and by carrying the etching further it is frequently possible to see the perfect uni- formity of orientation of the secondary crystals within each of these polyhedrons. As the boundary lines of these granules bear no relation to the internal structure of the same, they are called allotrimorphic crystals as com- pared with idiomorphic crystals, in which the external form corresponds to the internal symmetry, as is the case in the " pine-tree" crystals which I have just described. It is not within the scope of this paper for me to refer to the crystalline structure of cast iron, or to the small but perfectly formed crjstal structures frequently found in cast iron cavities. The crystalline structures that occur in iron rich in silicon or manganese have also little direct bearing on our subject. I may, however, refer to the so-called " furnace- crystals" or " bears " of carbonless, or almost carbonless Manchester Memoirs, Vol. Iv. (191 1), No. ^4. 13 iron, which are occasionally found in furnace hearths or slag masses. A good example of this formation was once sent to me by the late Mr. H. A. Hoy, which had been taken from a pocket in the hearth of one of the steel- melting furnaces of the Lancashire and Yorkshire Railway Company at their Horwich works. Prolonged exposure to a temperature not far removed from the melting point had oxidised away the carbon, silicon and manganese, whilst by absorption and concentration, the phosphorus content had increased to a remarkable extent as the following analysis of the sample shows : — Analysis of Horwich "'Furnace-Crystals''' ? Combined Carbon ... ... nil 7 Silicon ... Manganese Sulphur Phosphorus Iron trace „ nil „ •02 „ 36 „ 9962 „ The external appearance of the metal resembled a mass of crystal surfaces, mostly pentagonal, with smooth flat faces, some being of considerable size. These might, at first sight, appear to furnish proof of a definite form of crystallization, but this is not actually the case. Their formation was due to the constant growth of the granules under the combined influence of time and heat ; and the effects of expansion and contraction upon groups of such granules in their plastic condition produced the forms of pentagonal dodecahedra such as are produced by the compression of plastic spheroids. This would be helped by the liquation of the more fusible phosphide of iron between their cleavage planes. On breaking up the mass when cold the lines of fracture would be along the brittle 14 Lange, Some Remarkable Steel Crystals. films of the phosphide, thus clearly revealing the formation produced under the above circumstances. The examination under the microscope of the micro- structure of steel sections after polishing and etching, supplies other links of evidence of crystallization in a regular system. The microstructure of an unannealed steel casting in this way shows a pattern suggestive of trellis-work, the white (ferrite) lines forming angular figures. On examining the case-hardened portion of a mild steel bar, we shall find the excess of cementite showing as a series of fine straight lines forming frequently angles of 90 and 45 and occasionally angles of 60 degrees. Sections of quenched carbon steels show the well-known structure of martensite, which has the appearance of being built up of a system of needles running parallel to the sides of an isosceles triangle. On quenching a saturated steel from a high temperature, we obtain a structure of martensite and austenite exhibiting a most marked geometrical pattern of bands crossing at angles of 90 and 45 degrees. Stead has drawn attention to the similarity between the structure of overheated steel and that of un worked and untreated steel that has cooled normally from the liquid state. The internal crystalline structure of iron and steel has been the subject of a great amount of highly skilled investigation in recent years. The early studies and experiments of Tschernoff, Osmond, Sorby, Le Chatelier and Brinell, paved the way for the later researches of Stead, Roberts-Austen, Sauveur, Roozeboom, Arnold, Martens, Heyn, Carpenter, and others that have lifted the veil that once shrouded the complex phenomena of iron and steel, and have brought their mysteries within the scope of definite laws. Manchester Memoirs, Vol. Iv. (191 1), No. *Z4. 15 The demand for greater strength of structures, under the ever increasing stress of modern requirements, has also called into being the study and use of special alloy steels, and the same methods of organised scientific research that have been applied to the ferrous metals are now-a-days being employed to increase the efficiency and reliability of the non-ferrous metals with immense benefits to all the industries concerned. Mcmchesier Mevwirs, Vol. L V. {No. ^4). Plate I. Fis;- I. Steel "Pine-tree"' Crystals, found in cavity in riser of large steel casting. About ith actual size. Reproduced by kind permission of Messrs. I'iciers Ltd. Manchester Meii/oi?s^ Vol. L V. [No. *ZA). Plate II. Fig. 2. Longitudinal section of end of steel "pine-tree" crystal, etched in picric acid and photographed by reflected light. Scale = 2:1. )'. NICKLJ. STLt L INCOT 'v2a TENoIl r 39 rOM.^ ELASTJC Liv'n 71 \ ' Pig' 3- Steel ingot broken across to sh)vv columnar structure. PROCEEDINGS OF THE MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. General Meeting, October 4th, 19 10. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. Mr. E. L. Rhead, F.I.C, Lecturer on Metallurgy at the Municipal School of Technology, Mr. Grafton Elliot Smith, M.A., M.D., F.R.S., Professor of Anatomy in the University of Manchester, and Mr. F. H. Crewe, Assistant Science Master in the Municipal Secondary School, AVhitworth Street, were elected ordinary members of the Society. Ordinary Meeting, October 4th, 19 10. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. The following were amongst the recent accessions to the Society's Library : " Oxide of Zinc : its Nature, Properties, and Uses" by J. C. Smith (i2mo., London, 1909), presented by the Trade Papers Publishing Co., Ltd. ; ^^ Adolf Furtwangler," von P. Wolters (4to., Miinchen, 1910), presented ii Proceedings. {^October ^.th, igio. by the K. Academie der Wissenschaften Munchen ; '■'■ Astro- graphic Catalogue igooo. Oxford Sectioi Dec. + 2^° to + J2\" vols. 5, 6, by H. H. Turner (Fol., Edinburgh, 1909), presented by the University Observatory of Oxford; "■Flora Capensis^'' vol. 5, sect. I, part 2, by Sir W. T. Thiselton-Dyer (8vo., London, 1910), purchased; ^^ Historical Sketch [0/ t/ie] Museum of Natural History {Sptingfield), iSjg-iQog,'" by G. P. Johnson (8vo., Springfield, 1910), presented by the Springfield Museum ; "^ Reti-ospect of ^o years' Existence and Work {of the Liver- pool Geological Society) " hy \N . l\e\s\iX. (8vo., Liverpool, 1910), presented by the Liverpool Geological Society ; " Supplementary Investigation in igog of the Figure of the Earth and Isostasy^ by J. F. Hayford (410., Washington, 1910), presented by the U.S. Coast and Geodetic Survey; '•'■Celestial EJectamenta" by Dr. H. Wilde (Svo., Oxford, 1910), presented by the author; " CEuvres Completes'''' de C. Huygens. Tome 12 (4to., La Haye, 191 o), presented by the Societe Hollandaise des Sciences de Harlem ; A Reconnaissance across the Mackenzie Mountains, etc." by J. Keele (Svo., Ottawa, 1910), presented by the Geological Survey of Canada : " Onderzoekingen in Verband ??iet de Afschei- ding van Foezelolie," door F. Fontein (Svo., Delft, 1909), "■ Bif- drage tot de Kennis der Constitutie van het Bixine" door J. F. B. van Hasselt (Svo., Haarlem, 1910), '■'' Bijdrage tot de Kennis der Postcenomane Hypoalyssische,'" door J. Schmut/er (410., Amster- dam, 1910), and " De Bou7V van het Siliiur van Gotland," door E. C. N. van Hoepen (4to., Delft, 19 10), presented by the Technische Hoogeschool te Delft ; " Three JVisconsin Cushings," by T. W. Haight (8vo., n. pi., 1910), presented by the Wisconsin History Commission; ^'-Monograph of the British Nudi- branchiate Mollusca,'' part 8, by J. Alder, A. Hancock, and Sir C. Elliot (fol., London, 1910), purchased from the Ray Society ; ^^ Bacon is Shakespea?r'' by Sir E. Durning-Lawrence (Svo, London, 19 10), presented by the author ; " J J 'heat in India : Its Production., Varieties, and Iinprovement,'' l)y A. and G. L. C. Howard (Svo., Calcutta, iS:c., 1909), presented by the Agricul- tural Research Listitute of Pusa ; " Ethnographica in het Museum October ^th, [gio^\ I'ROCEEDINGS. iii van lici Bataviaasch Gcnoo/Si/ia/^" pis. 1-12, door J. W. Teillers (fol., VVeltevreden, 1910), presented by the Bataviaasch Genoot- schap van Kunsten en \\'etens(happen ; " Scrmones Domini- cales'\..elldtta Szilddy Aron, Kot. i, 2 (8vo., Budapest, 1910), presented by the Magyar 'rudomanyok Akadeniia ; " The Trade Winds of the Atlantic Ocean," by M. W. C. Hepworth, J. S. Dines and E. Gold (4to., London, 1910), presented by the Meteorological Office, London ; and " Geologic Atlas of the f/i.S'.," folios 16-56, 5869, 71-168 (la. fol, Washington, 1895- 1909), presented by the U.S. Geological Survey. Mr. Thomas Thorp described a method for preventing the tarnishing of silver-on-glass parabolic mirrors, which he had found very successful. The method was, briefly, as follows : — • The mirror was carefully levelled on a turntable, and its axis of rotation made coincident with that of the turntable. The whole was then rotated uniformly at the calculated speed required to cause a liquid to assume the same parabolic form as that of the mirror. A i % solution of " Schering's " celloidine in amyl acetate (after a lengthy period of settling) was flooded on to the surface of the mirror to a depth of about one-third of a millimetre. This was allowed to dry very slowly when the resultant film was found to have a perfectly even surface of a thickness of about ^-^ of a millimetre. On testing the mirror no perceptible loss of definition was observed, and in actual use the performance was satisfactory. It is absolutely essential for the success of the method that the mirror be quite enclosed, and exposed only to an atmosphere of amyl acetate, so as not to be allowed to dry, for about one hour after the solution has been flooded on, as, without this precaution, a perfectly uniform film cannot be obtained. Mr.C. E. SxROMiiYER, M. Inst. C.E., showed aprocess.nowfairly well known to metallurgists, by which the sulphide segregations in steel are reproduced on photographic paper which has been steeped in a weak solution of sulphuric acid and then placed on iv Proceedings. {October ^th, igio. the polished surface of the steel specimen. Twenty-seven impres- sions from samples of steel containing from o'03 to o"2o % of sulphur were exhibited, and it was pointed out that the varying intensities of the impressions were no safe guide to the percentage of sulphur present in the steel. Dr. Henry Wilde, F.R.S., read a paper entitled "On the Origin of Cometary Bodies and Saturn's Rings." The paper is printed in full in the Memoirs. General Meeting, October i8th, 1910. The President, Mr. Francis Jones, M.Sc, F.R.S.E., in the Chair. Mr. Robert McDougall, B.Sc. ; Mr. Robert Cotton, M.Sc, Demonstrator in Engineering in the University of Manchester, IVestho/me, Devonshire Road, Pendleton, Manchester; Mr. Evan Jenkin Evans, B.Sc, Assistant Lecturer and Demonstrator in Physics in the University of Manchester; Mr. Joseph Mangan, M.A., Lecturer in Economic Zoology in the University of Manchester ; Miss Edith May Kershaw, M.Sc, Demonstrator in Botany in the University of Manchester, Ash Meade, Upper Mill, Yorks. ; Mr. Walter Medley T.\ttersall, M.Sc, Keeper of the Manchester Museum, 34, Parsonage Road, Withington, Manchester; Mr. Roberto Rossi, M.Sc, Student, 2, Lime Grove, Oxford Road, Manchester; Mr. Robert Beattie, D.Sc, Lecturer in Electrotechnics in the University of Manchester ; and Mr. Arthur Lapworth, D.Sc, Lecturer in Chemistry in the University of Manchester, were elected ordinary members of the Society. October iSlh, igio.] Proceedings. Ordinary Meeting, October i8th, 1910. The President, Mr. Francis Jones, M.Sc, F.R.S.E., in the Chair. The thanks ot" the members were voted to the donors of the books upon the tables. Professor G. Elliot Smith, M.A., M.D., F.R.S., read a paper entitled, "The Convolutions of the Brain." It is well known that in a series of mammals belonging to the same family, the cerebral cortex is more extensive in the larger animals ; but the increase in the extent of the cortex does not remain proportionate to the bulk of the creature, because the size of the cerebral cortex is determined by the area of the sensory surfaces of the body which are relativety smaller in the larger animal. It is also well known that, in order that the blood vessels may convey to the cortex an abundant supply of nutriment, and, at the same time, cause a minimum amount of mechanical disturbance, the cortex does not increase in thickness to any extent, so that every addition to its bulk is expressed wholly in the expansion of its superficial area. It follows that in passing from the small smooth-brained members of any mammalian family to its larger representatives, the cortex must become folded in order to be packed in the limited area provided by the surface of the brain. It has now become possible to explain the nature of the factors which determine and guide the process 01 folding rendered necessary by these known fundamental conditions. In all mammals special parts of the cortex become cultivated by each of the senses — one area is set apart to act as a receptive and recording apparatus for impressions of sight, another for hearing, another for touch, another for smell, and so on. In the more highly organised mammals other areas become differentiated vi Proceedings. \^Odober iStli, igio. around each of these primary sensory territories to elaborate, as it were, the raw material received by the latter, and also to blend the various impressions, visual, auditory, tactile, olfactory, et cetera, of one object into a consciousness of all its properties, and to test and appraise their significance in the light of previous stimula- tions, the effects of which have been stored up in the various cortical areas. Thus it comes to pass that the cortex is mapped out into a great number of territories, differing in structure and function, and varying in size in ditTerent mammals, not only because the sense-organs themselves vary in size and acuteness in different creatures, but also because in different orders and families a sense organ of a given size will have a varying cortical representa- tion. Thus, if one were to take a dog and a baboon with eyes of the same size, the monkey will be found to possess a much larger cortical visual area than the dog. It is these differences which determine the varied plans ol cortical folding and the resulting varieties in the patterns of the convolutions in different mammals. Folding occurs most often along the boundary line between two areas of different structure and function. The difference in the rate of expansion of two such areas is no doubt the reason for this type of fissure formation- — limiting sulci. In the second place a rapidly growing cortical territory, meeting with obstruction to its expansion on all sides, may become buckled in, and so a furrow develops along its axis {i.e., within its area), instead of at its edges. This second class of furrow is much less frequent than the first class, and may be distinguished as the group of axial sulci. There is a third variety, which may be called the operculated sulcus, in which one lip projects over a submerged area. Sulci of this type are produced by the submerging of a specialised fringing territory surrounding a main sensory area. In the fourth place various mechanical factors come into operation to modify the form of furrows formed in one of these three ways, or even to produce new sulci. October i8t//, iqto.] Proceedings. vii By the application of these principles it is possible to inter- pret the meaning and the mode of formation of most of the furrows which subdivide the higher types of cortex into numerous convolutions. (leneral Meeting, November ist, igio. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. Mr. James S. Broome, Science Teacher in the Salford Secondary School, and Mr. Atherton Greville Ewinc; Mathrson, Mining Engineer, Gtiildhall Chambers, 38I40, Lloyd Street, Manchester, were elected ordinary members of the Society. Ordinary Meeting, November ist, 1910. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. Mr. R. L. Taylor, F.C.S., F.I.C., read the following papers, written by Dr. A. N. Meldrum, and communicated by Prof. H. B. Dixon, F.R.S. :— "The Development of the Atomic Theory, ii. The various Accounts of the Origin of Dalton's Theory, iii. Newton's Theory and its Influence in the XVIIIth Century." The papers are printed in full in the Memoirs. viii Proceedings. [Novemheri^th.igio. Ordinary Meeting, November 15th, rgio. The President, Mr. Francis Jones, M.Sc, F.R.S.E., in the Chair. The thanks of the members were voted to the donors of the books upon the tables. The following were amongst the recent donations to the Society's Library : " The Mineral Resources of the Phiiippine Islands'' [by] W. D. Smith and others (4to., Manila, 19 10), presented by the Bureau of Science, Manila; '■'' Rapporten van de Commissic. in Nederlandsch-Indic voor Oiid- heidkundig Onderzoek op Java en Madoera, igo8" (4to., Batavia, 1 910), presented by the Bataviaasch Genootschap van Kunsten en Wetenschappen ; " Catalogue of Hepatica. (Anacrogynce) iti the Manchester Museum'' by W. H. Pearson (8vo., Manchester, 1910), and " The Tomb of Two Brothers," by M. A. Murray, [with I Reports by Dr. J. Cameron and others (8vo., Manchester, 1910), presented by the Manchester Museum; '■'■Catalogue of the British Hymenoptera of the Family Chalcididcc," by C. Morley, (8vo., London, 1910), ^^ Guide to the British Vertebrates exhibited in the Dept. of Zoology of the British Museum (N.H.)," (8vo, London, 19 10), ^^ Guide to the Crustacea, Arachnida, Onvchophora, a7id Myriopoda exhibited in the Dept. of Zoology" (8vo., London, 1910), and "■ Afetnorials of Charles Dartvin: A Collection of MSS., etc., to commemorate the Centenary of his Birth, etc." 2nd ed. (8vo., London, 1910), presented by the Trustees of the British Museum. Dr. W. Makower read a paper, written in conjunction with Dr. S. Russ, entitled, " Note on Scattering during Radio- active Recoil." The paper is printed in the Memoiis. Mr. D. M. S. Watson, B.Sc, read a paper entitled " Upper Liassic Reptilia. Part IIL Microckidus and On the Genus Colymbosaurus." The paper will appear in the Memoirs. November jgth,igio.'\ PROCEEDINGS. ix General Meeting, November 29th, 19 10. The President, Mr. Francis Jones, M.Sc, F. R.S.E., in the Chair. Dr. Han^Geiger, of the Manchester University, was elected an ordinary Member of the Society. Ordinary Meeting, November 29th, 19 10. The President, Mr. Francis Jones, M.Sc, F.R.S.E., in the Chair. The thanks of the members were voted to the donors of the books upon the tables. Prof. Alfred Schwartz read a paper, written in conjunc- tion with Mr. Philip Kemp, M,Sc.Tech.j entitled, " Some Physical Properties of Rubber." The paper will appear in the Memoirs. Ordinary Meeting, December 13th, 1910. The President, Mr. F^rancis Jones, M.Sc, F'.R.S.E., in the Chair. The thanks of the members were voted to the donors of the books upon the tables. The following were amongst the recent accessions to the Society's Library. " Southern Hemisphere Surface-Air Circulation" by VV. J. S. Lockyer (fol., London, 1910), presented by the Solar Physics Committee, South Ken- sington ; " Catalogue of a Collection oj Rocks and Minerals from Natal and Zulu land, arranged stratigraphically" by F'. H. Hatch (8vo., Pietermaritzburg, 1909), presented by the Natal Museum; and " Catalogue of the Dante Collection in the Library of X Proceedings. {Deceinber ijth, igio. University College, London, ^^ by R. AV. Chambers (8vo., Oxford, 1910), presented by the University College Library, London. Mr. Philip Kemp, M.Sc.Tech., showed experimentally that pure rubber strip which had not been previously extended expanded on the application to it of heat, whereas rubber, which liad previously been stretched, on being warmed contracted slightly before it began to expand. Mr. G. P. Varlev, M.Sc. (Vict.), exhibited a specimen of Pavonazzo marble from Carrara containing black veins, which, on examination, were found to be crystallised hematite, and not graphite as was supposed. Miss Margaret C. March, K.Sc, read a paper, com- municated by Dr. G. Hickling, entitled, "A Preliminary Note on the Effect of Environment on Unio pictorum, U. iu)? I idles, and Anodonta cygnea." The paper will be printed in the Memoirs. Mr. D. M. S. Wat.son, M.Sc, read a paper entitled " Notes on some British Mesozoic Crocodiles." The paper will be printed in the Memoirs. Professor F. E. Weiss, D.Sc, F. L.S., communicated a note " On Sigillaria and Stigmariopsis." The author exhibited some specimens of axes of Sigillaria associated with Stigmarian bark. From the repeated occurrence of these specimens it was suggested that they represented the base of the aerial or the subterranean axes of Sigillaria, probably of the Eusigillaria type. The secondary wood was more copiously developed than is general in the aerial axes. The primary wood was of Sigillarian type, so that these Stigmarian axes have centripetal i)rimary wood, and their pithcasts would be striated like those described for Stigmariopsis. It was noticed that in some instances small axes were found in contiguity, and apparently in continuity, with the main axes. These smaller axes resemble the ordinary Stigmarian axes vei) nearly, and do not show the centripetal primary wood of the main axis, but only a few fine tracheids in the pith region. January loth, ipri.] PROCEEDINGS. xi General Meeting, January loth, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. Mr. J. Stuakt Thomson, Ph.D. (Bern), Senior Demonstrator in Zoology in the Victoria University of Manchester ; Mr. Frank PlayfaiR Burt, B.Sc. (Lond.), Assistant Lecturer and Demon- strator in Chemistry in the Victoria University of Manchester, 5, Beaconsfield, Derby Road, ]Vithington ; Mr. Fredericic Russell Uankshear, B.A., of N.Z. University, Demonstrator in Chemistry in the Victoria University of Manchester ; and Mr. Robert Robinson, D.Sc. (Vict.), Teacher of Chemistry in the Victoria University of Manchester, Field House, Cliesterfieldy were elected ordinary members of the Society. Ordinary Meeting, January loth, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. The following were amongst the recent accessions to the Society's Library : " Enianuelis Swedenborgii Opera Foeiica" (8vo., Upsaliae, 1 910), and "-£". Stvedenborg' s Ffivestigations in Natural Science, and the basis for his State- ments concerning the Functions of the Brain " byM. Ramstr6m(4to., Uppsala, 19 10), presented by the Bibliotheque de I'Universite d'Uppsala ; " A Monograph of the British Annelids. Vol. 2, part 2. Polychaeta. Syllidx to Ariciidce^^ pp. 233-524; pis. 51-56 coloured, and 71-87 uncoloured, by W. C. Mcintosh (fol., London, 1910), purchased from the Ray Society; " Geologic Atlas of the U.S.," folios 169-173 (la. fol., Washington, 1909-1910), presented by the U.S. Geological Survey; "(?/(? xii Proceedings. {^Jamiary lot/i, igii. Rdmers Adversaria^' ...'\}^g\\\\Q....\&^ T. Elbe og K. Meyer (4to., Kobenhavn, 1910), presented by the Kgl. Danske Videns- kabernes Selskab ; " Aiitiqiiities of Central and South-Eastern Missouri^' by G. Fowke (8vo., Washington, 19 10), and ^''Chippewa Music" by F. Densmore (8vo., Washington, 1910), presented by the Bureau of American Ethnology. Mr. Fr.\ncis Nicholson, F.Z.S., read the following com- munication.— "Dr. Adam Bealey and Dr. Dalton." About sixteen years ago I happened to be in the Society's house when an elderly gentleman, accompanied by another of about his own age, who I understood was a cousin, came in to visit the place where, sixty years earlier, he had received lessons in chemistry from Dr. Dalton. The visitor introduced himself as Dr. Adam Bealey, and, in the course of conversation, mentioned that he possessed a small bust of Dr. Dalton, which, at my suggestion, he readily agreed to present to the Society. Shortly afterwards the bust was received by the Society, and placed, as desired by Dr. Bealey, in the room on the ground floor on the left as you enter, where it now is on the chimney-piece. A reproduction of a full size photograph of the bust accompanies this note. As Dr. Bealey's letters to me in connection with this gift are interesting, I have pleasure in presenting them to the Society, if they will accept them. Below are copies of the three letters : — Filsham Lodge, Filsham Park, Jany. 30th, 1894. Dear Sir, — I purpose to send to you the little bust of Mr. Dalton, by I'ickford's to-morrow. I shall be glad if it may be placed in the room in which we formerly sat to read with him. There is a little book published by Mr. Dalton of which he was personally more proud than of the New System of Chemical Philosophy. It is an English Grammar. If you have not a copy in the Lil)rary and would like this I will send it with pleasure. Yours faithfully, Adam Beai.ey. MancJicstcr Mevwtrs, Vol. L V., Proceedijigs. Plate John Dalton. January lotJi, ign.] PROCEEDINGS. xiii St. Leonard's-on-Sea, Eilsham Lodge, February I5fli, 94. Dfar Sir, — I was glad to hear from you tliat tlie Bust liad arrived safely. I will send the Grammar as soon as I can find it. I was many years in finding a cojiy. The bust is not Ivory and will require great care in cleaning. We were assured by Mr. Clare, Dr. DaltcMvs Executor, that the mould was broken up when twelve were cast. I do not know who had the others. Dr. Dalton was proud of his little Grammar but knew w'ell the difference between it and his New Chemical Philosophy, by which, as Lord Brougham described it, "he gave numerical laws to Chemistry and raised [it] from an Art to a Science." Yours faithfully, Adam Bealey. Filsham Lodge, St. Leonard's-on-Sea, Jany. 29th, 1902. Dear Sir, — In reply to your note, unfortunately so long unanswered, I reply Dr. Dalton always gave us our lessons in Chemistry in the room on the left on the ground floor. The adjoining room on the same floor contained some apparatus, such as a pneumatic trough, but not much other, so far as I can remember. I never was in the upper room, except on occasion of his public lectures, when few attended. He was more proud of his English Grammar than of his New System of Chemical Philosophy. If you would like to have my copy of his Grammar I will send it to you. For many years I kept ihe memoranda of his fees. One and sixpence a lesson ! ! When in acknowledgment of his skill and reputation and valuable advice in business my mother presented [him] with a cheque for ^{,"20, and I had the great pleasure of presenting it to him, he blushed and said, "but thou'l want some change out of this." This at a time when an introduction in Paris would have been more valuable than Lord Palmerston's. I intended to present the memoranda of fees to the British Museum, but in changes of residence they have been lost. Yours faithfully, Adam Bealey. Though so slight, Dr. Bealey's recollections of the great chemist show vividly the kind of man Dalton was. A chemist xiv Proceedings. ^January loth ign. of world-wide fame, content to charge eighteenpence a lesson, and having qualms of conscience about receiving a fee of ;^2o ! Dr. Bealey was the son, I am informed by Mr. William Hewitson of Bury, of Adam Bealey (£781-1821), by his wife Mary Williams, who died at her son's house, in Tavistock Square, London, 15th February, 1858. His grandfather was Richard Bealey, of Radcliffe, and his great grandfather was Joseph Bealey, of Radcliffe. Adam Bealey, M.A., M.D., F.R.C.P., was born about 1813. He was educated at Cambridge, first at St. John's College, and afterwards at Queens'. He also studied at St. George's and Guy's Hospitals. For some time he was actively interested in a paper-works at Prestolee, belonging to the Bealey family. Later he was in practice as a physician, in Harrogate, and on retiring went to live at St. Leonard's-on-Sea, where he died 5th March, 1905, aged 92, leaving a widow and children. Mr. H. S. HoLDEN, B.Sc, F.L.S., read a paper communi- cated by Prof. F. E. Weiss, D.Sc, F.L.S., entitled "On an Abnormal Fertile Spike of Opliioglossum vulgatjun.'' Mr. R. L. Taylor, F.CS., F.LC, read a paper, written by Dr. A. N. Meldrum, and communicated by Prof. H. B. Dixon, M.A., F.R.S., entitled "The Development of the Atomic Theory : (4) Dalton's Physical Atomic Theory " Both papers are printed in full in the Alemoirs. Ordinary Meeting, January 24th, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to" the donors of the books upon the tables. Janiiayv 2^th,igii'.\ PROCEEDINGS. xv In accordance witli a resolution passed liy the Council earlier in the day the President made the following communi- cation to the Members : — " The Council has decided to make known to the Members of the Society the causes which have prevented the publication of the Wilde Lecture for 1910. The lecture was delivered on IMarch 22nd by Sir Thomas Henry Holland, who, on June 29th, received a letter from Messrs. Slater, Heelis & Co., Solicitors, acting for Dr. Henry Wilde, F.R.S., requesting the immediate delivery to the Society of the manuscript of the lecture for publication, or the return of the honorarium. This was followed on July ist by an intimation from the same solicitors that at Dr. Wilde's request they had issued a writ against Sir Thomas Holland, who promptly instructed his Solicitors to accept service. This writ has not been served, but Sir Thomas Holland decided not to forward the manuscript unless the writ were withdrawn unconditionally. Two other actions have been commenced by Dr. Wilde, one against the Society and the other against Dr. Hickling, one of the Secretaries. The latter, however, has been formally dis- continued. Under these circumstances the Council has reluctantly resolved that it is not desirable to nominate a Wilde Lecturer for 191 1." Mr. R. L. Taylor, F.C.S., F.LC, read a paper, written by Dr. A. N. Melurum, and communicated by Prof. H. B Dixon, M.A., F.R.S., entitled "The Development of the Atomic Theory : (5) Dalton's Chemical Theory." Prof. J. E. Petavel, D.Sc, F.R.S., read a paper, written by Prof. A. H. Gibson, D.Sc, entitled "The Behaviour of Bodies Floating in a Free or a Forced Vortex." Both papers are printed in full in the Memoirs. XVI Proceedings. {^February ph,i git. Ordinary Meeting, February 7th, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. Mr. J. H. WoLFENDEN, B.Sc, and Mr, H. E. Schmitz, M.A., B.Sc, were nominated auditors of the Society's accounts for the session 1910-1911. Prof. W. Boyd Dawkins, D.Sc, F.R.S., made a short communication on the origin of the Roman numerals I.-X., in which he suggested that they were derived from a system of numeration employed by the inhabitants of Crete during the Minoan civilisation. This conclusion was based on a comparison of the Roman numerals with a set of Minoan numerical symbols which Sir Arthur Evans, the distinguished excavator of Crete, had shown to Prof. Dawkins. Mr. Robert Cotton, M.Sc, read a paper written by Prof A. H. Gibson, D.Sc, entitled ''The Manner of Motion of Water Flowing in a Curved Path." Miss Margaret C March, B.Sc, read a paper, communi- cated by Dr. George Hickling, entitled " Studies in tne Morphogenesis of certain Pelecypoda. II. The An- cestry of the Gibbosae." Both papers are printed in full in the Memoirs. Ordinary Meeting, February 21st, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. February 21st, igii.'] PROCEEDINGS. xvii Dr. Alfred Holt, M.A., read a paper entitled "The Boric Acids." The paper is printed in full in the Memoirs. Mr. J. E. Myers, B.Sc, read a paper, written in con- junction with Dr. A. Holt, entitled "The Hydration of Metaphosphoric Acid," of which the following is an abstract. Experiments were described by which it was shown that pyrophosphoric acid is formed as an intermediate compound in the hydration of metaphosphoric acid. It was further shown that the hydration did not take place according to any simple scheme, and a method of estimating meta acid in a solution of all three varieties by means of barium chloride was described. From the depression of the freezing point of aqueous solutions of various varieties of pyro and meta acids it appears that, when these acids are prepared by dehydration of ortho- phosphoric acid, there occurs association of the molecules, but when prepared by decomposition of the lead salts by hydrogen sulphide, simple molecules result. The peculiar "crackling" phenomenon which accompanies the solution of one form of meta acid was shown. Ordinary Meeting, March 7th, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. The President referred to the loss the Society had sus- tained through the death of Professor J. H. van't Hoff, the celebrated Dutch Chemist, who had been an Honorary Member since 1892, and was present at the dinner in 1903 when the xviii Proceedings. {^Mardi jth, igii. Society celebrated the centenary of the discovery of Dalton's atomic theory. Professor van't Hoff was best known for his work on Stereo-isonierism, and the theory advanced by him to explain these phenomena is now generally accepted by chemists. Professor G. Elliot Smith, F.R.S., exhibited a cast of the Gibraltar skull— the most complete palaeolithic skull known — now in the Museum of the Royal College of Surgeons. It was hewn out of a terrace of solid conglomerate limestone, under the north face of the Rock of (iibraltar, by the Royal Engineers in 1848; but was only cleaned of its matrix and properly dis- played last year by Professor Arthur Keith, of the Royal College of Surgeons, to whom Prof. Elliot Smith was indebted for this cast. The outstanding features of this skull are (1) its small brain capacity (1060 cc); (2) the great supra-orbital ridge of bone and the low receding forehead; (3) the great orbits and nose, larger than those of modern races ; (4) the blown out appearance of the face due to the great development of the air spaces of the upper jaw; and (5) the very slight development of the mastoid process. Professor E. Rutherford, F.R.S., read a paper entitled " The Scattering of the « and /3 Rays and the Structure of the Atom," of which the following is an abstract. It is well known that the a and /3 particles are deflected from their rectilinear path by encounters with the atoms of matter. On account of its smaller momentum and energy, the scattering of the /3 particles is in general far more pronounced than for the a particles. There seems to be no doubt that these swiftly moving particles actually pass through the atomic system, and a close study of the deflexions produced should throw light on the electrical structure of the atom. It has been usually assumed that the scattering observed is the result of a multitude of small scatterings. Sir J. J. Thomson {Froc. Cam. Phil. Soc, 15, Pt. 5, 1910) has recently put forward a theory of small scattering, and the main conclusions of the theory have been experimentally examined by Crowther for /3 rays {Froc. Roy. Sac, March yf/i, iqit.] Proceedings. xix 84, p. 226, 1 910). On this theory, the atom is supposed to consist of a positive sphere of electrification containing an equal quantity of negative electricity in the form of corpuscles. By comparison of theory with experiment, Crowther concluded- that the number of corpuscles in an atom is equal to about three times its atomic weight in terms of hydrpgen. There are, how- ever, a number of experiments on scattering, which indicate that an a or /? particle occasionally suffers a deflexion of more than 90" in a single encounter. For example, Geiger and Marsden {Proc. Roy. Soc, 82, p. 495, 1909) found that a small fraction of the a particles incident on a thin foil of gold suffers a deflexion of more than a right angle. Such large deflexions cannot be explained on the theory of probability, taking into account the magnitude of the small scattering experimentally observed. It seems certain that these large deviations of the n particle are produced by a single atomic encounter. In order to explain these and other results, it is necessary to assume that the electrified particle passes through an intense electric field within the atom. The scattering of the electrified particles is considered for a type of atom which consists of a central electric charge concentrated at the point and surrounded by a uniform spherical distribution of opposite electricity equal in amount. With this atomic arrangement, an « or /3 particle, when it passes close to the centre of the atom, suffers a large deflexion, although the probability of such large deflexions is small. On this theory, the fraction of the number of electrified particles which are deflected between an angle 0 and 0 + d(p is given by -jifi)"' cot 0/2 cosec" (/>/2^0 where /i is the number of atoms 4 per unit volume of the scattering material, t the thickness of material supposed small, and 6= , where iVe" is the charge at mir ° the centre of the atom, E the charge on the electrified particle, m its mass, and // its velocity. It follows that the number of scattered particles per unit area for a constant distance from the point of incidence of the pencil of rays varies as cosec''(/)/2. This law of distribution has XX Proceedings. {^March yfli, igii, been experimentally tested by Geiger for a particles, and found to hold within the limit of experimental error. From a consideration of general results on scattering by 'different materials, the central charge of the atom is found to be very nearly proportional to its atomic weight. The exact value of the central charge has not been determined, but for an atom of gold it corresponds to about loo unit charges. From a comparison of the theories of large and small scattering, it is concluded that the effects are mainly controlled by the large scattering, especially when the fraction of the number of particles scattered through considerable angles is small. The results obtained by Crovvther are for the most part explained by this theory of large scattering, although no doubt they are to a certain extent influenced by small scattering. It is con- cluded that for different materials the fraction of particles scattered through a large angle is proportional to NA" where N is the number of atoms per unit volume, and A the atomic weight of the material. The main results of large scattering are independent of whether the central charge is positive or negative. It has not yet been found possible to settle this question of sign with certainty. This theory has been found useful in explaining a number of results connected with the scattering and absorption of a and /3 particles by matter. The main deductions from the theory are at present under examination in the case of the a rays by Dr. Geiger using the scintillation method. Dr. H. Geiger read a paper entitled " The Large Scattering of the « Particles," of which the following is an abstract. Geiger and Marsden have shown that a small fraction of the o particles incident on a thin film of matter are so scattered that they emerge again on the side of incidence. In the present paper the fraction of the a particles scattered through various large angles by a thin gold foil has been experimentally March yth, ipii.] PROCEEDINGS. xxi determined by the scintillation method. Radium emanation enclosed in a fine glass tube was used as a source. The microscope to which the zinc sulphide screen was attached moved round the arc of a circle ; the distance between the scattering material and the screen was constant and equal to about 2 cms. The source of radiation, the scattering foil, and the screen were enclosed in a metal vessel which was exhausted to a low pressure. The number of o particles scattered through large angles up to 150° was first measured, and, as the emanation decayed, the number of small angles was successively determined. The number of scattered particles per unit area varied, when corrected for decay, nearly 300 times over the range of angles examined. The actual numbers of particles observed varied very approximately as cosec^0/2 where ^ is the angle of deflection. This is the relation theoretically deduced by Professor Rutherford in the foregoing paper. Experiments are in progress to examine the other deductions of the theory, and especially the variation of the amount of large scattering with thickness and nature of scattering foils and velocity of the a particles. Mr. R. F. GwYTHER, M.A., read a paper entitled " Can the Parts of a Heavy Body be supported by their Elastic Reactions only ? " The paper is printed in full in the Memoirs under the title "The Conditions that the Stresses in a Heavy Body should be purely Elastic Stresses." Ordinary Meeting, March 21st, igii. Mr. Francis Jones, ]\[.Sc., F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. The following were amongst the recent xxii Proceedings. {^MarcJi 21st, igii. donations to the Society's Library : " Istar ii/id Gi/gamos. Babiloiiische Sage." — Aus dem Ungarischen des Arpad Zempleni ins Deutsche iibertrag. von J. Lechner von der Lech (i6mo., Budapest, 1911), presented by the author ; " Codex diploinatiais Litsatict superioris ///."... Hft. 6, herausg. von R. Jecht (8vo., GorUtz, 1 910), presented by the Oberlausitzische Gesellschaft der Wissenschaften, Gorlitz ; " Die Reise der deutscheii Expeditiojt ziir Beobachtiing des Vcnusdiirchgaiiges am p -Deg. 1S/4," von Dr. L. Weinek (4to., Prag, 19^1), presented by the K. K. Stern- warte in Prag; " Carl vou Voif,'^ von O. Frank (4to., ISTunchen, 1910), presented by the K. Akademie der Wissenschaften of Munich ; " Sixth Report on Research JJ'orh on .. .Typhoid bacilli^^ by Dr. A. C. Houston (8vo., [London], 1910), presented by the Metropohtan Water Board ; " Rapport siir V Expedition Polairs Neerlandaise...T8S2\83" par M. Snellen et H. Ekama (fol., Utrecht, 19 10), presented by the Kon. Nederland. Meteorology Institut, Utrecht; '■'■ Les Prix Nobel, igoS" (8vo., Stockholm, 1909), presented by the K. Svensk. Vetenskaps Akademie Stock- holm ; " Report on a part of the iV. JF. Territories drained by the Winisk and Attawapiskat" by W. Mclnnes (8vo., Ottawa, 1910), presented by the Geological Survey of Canada ; " Handbook of American Indians North of Mexico f part 2, ed. by F. W. Hodge (8vo., Washington, 19 10), presented by the Bureau of American Ethnology ; and the following six pamphlets by Ch. Janet : '■'• Sur la Morphologic de PInsecte" (4to., Limoges, 1909), ^' Sur I'Ontogenese de PInsecte" (4to., Limoges, 1909), ^^ A^otc sur la Phylogenese de rinsecte'" (Svo., Rennes, 1909), '■''Sitrla Morphologic des Membranes Basales de V Insecte" (8vo., Beauvais, 1909), ^^ Sur la Parthenoginese arrhenotoque de la Four mi ouvriere " (8vo., Beauvais, 1909), and '■'■Sur un Nematode qui se developpc dans la tete de la Formica fu sea " (8vo., Beauvais, 1909), presented by the author. Mr. William Thomson, F.R.S.E., F.C.S., read a paper entitled: "On the Influence of Atmospheric Pressure and Humidity on Animal Metabolism." March 21st, ipii.] PROCEEDINGS. xxiii In a previous paper the author stated he had found that the percentage of Carbonic Acid gas contained in the exhaled air from the lungs was greater when breathing dry than when breathing damp air, also when breathing in Mountainous districts where the atmospheric pressure was low than when breathing in the Valley, and, again, was greater when breathing in the Valley than when breathing at the bottom of a deep Coal pit where the pressure is still greater. The experi- ments recorded in the present paper were made upon the exhaled air from three men and one boy, and upon guinea pigs and mice, and the results from all shew that, as a rule, when the barometer fell, the percentage of Carbonic Acid in the exhaled air rose, and, when the barometer rose, the percentage of Carbonic Acid fell. As the air became more moist the per- centage of Carbonic Acid fell, and it rose when the air became drier. There was a lower percentage of Carbonic Acid in the exhaled air when the weather was warm than when it was cold. The paper will be published in full in the next volume. Miss Margaret C. March, B.Sc, read a paper, communi- cated by Dr. Hickling, entitled : " Studies in the Morpho- genesis of certain Pelecypoda. III. The Ornament of In'goma davellata and some of its Derivatives." The paper is printed in full in the Alemoirs. General Meeting, April 4th, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. Mr. Arthur Adamson, A.R.C.S., Lecturer in Physics in the Municipal School of Technology, Manchester, and Mr. C. G. Darwin, B.A., Reader in Mathematical Physics in the University of Manchester, were elected ordinary members of the Society. xxiv Proceedings. [April ^th, ign. Ordinary Meeting, April 4th, 191 1. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. Professor F. E. Weiss, D.Sc, F.L.S., exhibited a hybrid of the Oxlip {Primula elatior) and the Primrose {Primula acaulis) collected by him in Cambridgeshire last year, where such plants are very common in the woods in which both the parental species occur. The hybrid bears its flowers in clusters on an erect scape as in the oxlip, but the flowers are much larger and paler, and resemble in their size and marking those of the primrose. The offspring of the hybrid (fa generation) showed a number of different forms, some resembling the parent hybrid but with a considerable range of variation in the size and colour of the flowers. Most of the plants bore all their flowers on scapes, but others only showed radical flowers and seemed therefore to have reverted to the primrose type. The scape must therefore be regarded as a dominant character, as it appears in the presumptive fi generation and also in the majority of plants of the iz generation. All the individuals of this genera- tion have not flowered yet, but among the early flowering individuals were some possessing both radical and cauline flowers, and one of the primrose type with pure white petals. Professor W. W. Haldane Gee read a paper, written in conjunction with Mr. A. Adamson, A.R.C.S., entitled " Dioptriemeters." The paper is printed in full in the Memoirs. Professor E. Knecht, Ph.D., read a note "On the Action of Hydrogen Peroxide on Quinone." It was shown that when hydrogen peroxide is allowed to act on quinone in presence of ammonia, the solution becomes heated and a April 4-th, igii?\ Proceedings. xxv brisk evolution of oxygen takes place. On acidulating the solution and extracting with ether, hydroquinone was found to have been formed in considerable amount. Toluquinone behaves in a similar way to ordinary quinone. Mr. R. L. Taylor, F.C.S., F.I.C., communicated a paper written by Dr. A. N. Meldrum, entitled "The Develop- ment of the Atomic Theory : (6) The Reception accorded to the Theory as advocated by Dalton." The paper is printed in full in the Alemoirs. The reading of Dr. Meldrum's paper on " The Develop- ment of the Atomic Theory : (7) The Rival Claims of "William Higgins and John Dalton to the Chemical Theory," was postponed till the Meeting of April 25th. Annual General Meeting, April 25th, 191 1. Mr. Francis"Jones, M.Sc, F.R.S.E., President, in the Chair. The Annual Report of the Council and the Statement of Accounts were presented, and it was resolved : — " That the Annual Report, together with the Statement of Accounts, be adopted, and that they be printed in the Society's Proceedings. Mr. T. G. B. Osborn and Mr. E. L. Rhead were appointed Scrutineers of the balloting papers. The following members were elected officers of the Society and members of the Council for the ensuing year : — President: F. E. Weiss, D.Sc, F.L.S. Vice-Presidents : Francis Jones, M.Sc, F.R.S.E. ; Ernest Rutherford, D.Sc.,F.R.S. ; Arthur Schuster, Sc.D., Ph.D., F.R.S. 3 Francis Nicholson, F.Z.S. xxvi Proceedings. {April 25th, igii. Secretaries : R. L. Taylor, F.C.S., F.I.C. ; George Hick- ling, D.Sc. Treasurer: William Henry Todd. Librarian: C. L. Barnes, M.A. Other Members of the Council: Edmund Knecht, Ph.D. ;, William Burton, MA., F.C.S. ; Sydney J. Hickson, M.A., D.Sc, F.R.S. ; Sir Thomas H. Holland, K.C.I.E., D.Sc, F.R.S. ; Thomas Thorp, F.R.A.S. ; and T. A. Coward, F.Z.S. Ordinary Meeting, April 25 th, 1911. Mr. Francis Jones, M.Sc, F.R.S.E., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. The following were amongst the recent donations to the Society's Library: "■Synopsis of the Sections Microporus, Tabacinus and Funales of the Genus Pofystictusi" and ^'■Synopsis of the Ge?ius JIexago}ta" by C. G. Lloyd (8vo. , Cincinnati, 19 lo), presented by the Lloyd Library ; " Catalogue of Eg)ptia7i Antiquities of the XII. and XVIII. Dynasties in the Manchester Museum" hy A. S. Griffith (8vo., Manchester, 1910), and " Outline Classification of the Animal Kingdo?n" 4th ed., by S. J. Hickson (8vo., Manchester, 191 1), presented by the Museum; '^ A Herbert Bibliography" by G. H. Palmer (8vo., Cambridge, Mass., 191 1), presented by Harvard University Library ; ''Photography " by A. Brothers, 2nd ed. (8vo., London, 1899), presented by the author ; "• Nefstarsi Brevidr Chrvatsko- Hlaholsky" by J. Vajs (8vo., Praze, 19 10), and '' U'nte?'suchungen fiber den Lichtwechsel iilterer veranderlichen Sterne^" vol. i, von VojtechSafarik (fol., Prag, 1910), presented by the K. Bohmische Gesellschaft, Prague, and " Life and Scientific Work of Peter April 2^th, igii.'] Proceedings. xxvii ■Guthrie Tait,'' by C. G. Knott (4to., Cambridge, 191 1), presented by Mr. W. A. Tait. Prof. F. E. Weiss, D.Sc., F.L.S., exhibited a specimen of the fungus Gyninosporavgimn parasitic on the common Juniper. This fungus appears in spring in the form of orange-coloured, finger-like processes on the stem and branches of the Juniper, and its spores are then carried by the wind to the leaves of the Mountain Ash or Hawthorn, on which it lives parasitically •during the summer. It completes its life-history by re-infecting the Juniper in the autumn. Dr. G. HiCKLiNG read a paper, written by Dr. Henry Wilde, F.R.S,, entitled ''On the Periodic Times of Saturn's Rings." The paper is printed in full in the Memoirs. Mr. R. L. Taylor, F.C.S., F.I.C., communicated a paper, written by Dr. A. N. Meldrum, entitled "The Development of the Atomic Theory : (7) The Rival Claims of William Higgins and John Dalton to the Chemical Theory." The paper is printed in the Alemoirs. General Meeting, May 9th, 191 1. Mr. Fran-CIS Jones, M.Sc, F.R.S.E, Vice-President, in the Chair. Mr. Henry Gwyn Jeffreys Moseley, Lecturer in Physics in the Victoria University of Manchester, Dunwood House, Withington, and Mr. Gilbert Cook, Vulcan Research Fellow in Engineering in the Victoria University of Manchester, 8, Clarendon Road, Garston, Liverpool, were elected ordinary members of the Society. Proceedings. [Maj> p//i, igii. Ordinary Meeting, May gth, 19x1. Professor F. E. Weiss, D.Sc, F.L.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the tables. Mr. Ernest F. L.\nge, M.I.Mech.E., F.C.S., read a paper entitled " Some Remarkable Steel Crystals " The paper is printed in the Memoirs under the title "An Account of some Remarkable Steel Crystals, along with some Notes on the Crystalline Structure of Steel." Professor S. J. Hickson, D.Sc, F.R.S., read a paper entitled " On a specimen of Osteocella Septentrionalis (Gray)." The papers are printed in full in the Me7noirs. A7i7i7ial Report of the Coimcil. xxix Annual Report of the Council, April, 1911. The Society began the session with an ordinary membership of 145. During the present session nineteen new members have joined the Society. Thirteen resignations have been received. This will leave on the roll at the end of the session 151 ordinary members. One honorary member also has been elected, viz. : Geh. Professor Dr. Walter Nernst. The Society has lost, by death, three honorary members, viz. : Professor Stanislao Cannizzaro, For.Mem.R.S., Professor J. H. van't Hoff, Ph.D., For.Mem.R.S., and Sir William Huggins, O.M., K.C.B., F.R.S., and one corresponding member, viz., the Rev. Robert Harley, F.R.S. Memorial notices of these gentlemen appear at the end of this report. The average attendance at the meetings was 21, the same as for the session 1909-10. The Society commenced the session with a balance in hand of ^368. 3s. 4d., from all sources, this amount being made up of the following balances : — At the credit of General Fund p^io2 9 9 „ ,, Wilde Endowment Fund... 179 9 7/ „ ,, Joule Memorial Fund 86 4 o ;^368 3 4 The total balance in hand at the close of the session amounted to ^304. 7s. 8d., and the amounts standing at the XXX Annual Report of the Council. creditor the separate accounts, on the 31st March, 191 1, are the following : — At the credit of General Fund ;^62 11 6 „ ,, Wilde Endowment Fund... 149 12 4 „ „ Joule Memorial Fund 92 3 10 Balance 31st March, 1911 ;^304 7 8 The Wilde Endowment Fund, which is kept as a separate banking account, shows a balance of ;z{^ 149. 12s. 4d. in its favour, as against ;^i79. 9s. yd. at the beginning of the financial year, the receipts from the invested funds being the same as those for the previous year. The Librarian reports that during the session 704 volumes have been stamped, catalogued and pressmarked, 656 of these being serials, and 48 separate works. There have been written 189 catalogue cards, 125 for serials, and 64 for separate works. The total number of volumes catalogued to date is 33,082 for which 11,731 cards have been written. Satisfactory use is made of the library for reference purposes. During the session, 185 volumes have been borrowed from the library, as compared with 202 in the previous session. Further attention has been given to the completion of sets, 46 volumes and parts having been obtained, which complete two sets and partly complete two others. These were presented by the societies publishing them. A larger amount of binding has been done this session, 214 volumes having been bound in 167. A record of the accessions to the library shows that, from April, 1910, to March, 191 1, 758 serials and 67 separate works were received, a total of 825 volumes. The donations during Annual Report of the Council. xxxi "the session (exclusive of the usual exchanges) amount to 66 volumes and 152 dissertations; one volume has been purchased •(in addition to the periodicals on the regular subscription list). The following new serial publications have been received during the past session : — University of Missouri Studies. Literary and Linguistic Series ; Science Conspectus, published by the Massachusetts Institute of Technology j and Matiiematical Motes, published by the Edinburgh Mathematical Society. The Library has also been presented by the U.S. Geological Survey with a copy of one hundred and fifty-eight folios of the ' Geologic Atlas of the United States.' A new and complete catalogue of the serial publications ^received by the Society has been in progress for several months, and will shortly be issued. Some idea of its extent may be gathered from the fact that the total number of jmblications actually in progress is 808, of which 186 are from the British Islands, 165 from the U.S.A., 95 from Germany, 60 from France, 40 from Italy, 34 from Austria-Hungary, and so on. The problem of ifinding shelf room for the enormous mass of literature possessed by the Society will ere long become urgent. The Society is indebted to Mr. Francis Nicholson, F.Z.S., 'for presenting to it three letters written to him in 1894 and 1902 by Ur. Adam Bealey, a former pupil of Dalton, explaining the circumstances under which Dr. Bealey gave to the Society •a small bust of Dalton now exhibited in one of its rooms. The letters also give interesting glimpses of Dalton himself, and show what small fees the great scientist charged for the lessons ihe gave his pupils. The publication of the Memoirs and Pi-oceedings has been ■continued under the supervision of the Editorial Committee. During the summer extensive decorations and repairs were •carried out on the Society's premises, and the Society is greatly xxxii Annual Repoi't of the Council indebted to Dr. H. Wilde, F.R.S., for the time and attention he bestowed in undertaking the business arrangements and super- vision of them. The cost, amounting to £,\\o. 13s. 5d., has been charged to the Wilde Endowment Fund. It is with great regret that the Council report that Mr. Arthur McDougall has intimated his intention of resigning the Treasure! ship at the end of the present session, and desires to record its thanks for his care of the Society's finances during the eight years that he has held ofifice. Mr. McDougall has been reluctantly compelled to take this step by the urgency of his health, the state of which has for some time made him wish to be relieved of the duties of his office, and he latterly only continued to discharge these at the earnest request of his fellow members of Council and at some sacrifice to himself Stanislao Cannizzaro, an honorary member of the Society from the year 1888, was born in 1826, and was a native of Palermo, in Sicily. After having studied medicine in his native town for four years, he turned his attention to chemistry, and worked at Pisa as assistant to Piria. On the outbreak of the Sicilian revolution, in 1848, he acted as an officer of artillery, and was elected a Deputy to the Sicilian Parliament. When the revolution was crushed in the next year, he escaped to Marseilles,, and made his way to Paris. In Paris he worked in Chevreul's laboratory, making an investigation along with Cloez of the substance cyananide. In the year 1851 he was appointed Professor of Chemistry at Alexandria; from there he went to Genoa in 1855, and to Palermo in 1861. In 1871 he was elected to the Chair of Chemistry at Rome, and this position he held to the end of his life. He served his country also as a member of the Italian Senate, of which he became Vice-President, and as a niember of the Council of Public Instruction. He died in the year 1910. Annual Report of the Coimcil. xxxiir The experimental work which he published was chiefly in the region of organic chemistry. An important reaction which he discovered, is that in which an aromatic aldehyde is converted by treatment with caustic potash into the corresponding acid and alcohol : benzaldehyde, for instance, yields benzoic acid and benzylic alcohol. One may mention also the series of researches which he carried out on santonin and its derivatives. Cannizzaro was greatest as a teacher of chemistry. At the time he began his career the science was in a chaotic state. The objection to the atomic theory, as that theory was understood between the years 1808 and i860, was that the chemical formulae of substances and the atomic weights of the elements were decided in tin arbitrary way. Thus there had arisen three great systems of chemical formula, each with much in its favour, that of Berzelius, that of Gmelin, and that of Gerhardt and Laurent. The attempts which were made at compromise between these different systems only resulted in heightening confusion. Cannizzaro's contribution to the philosophy of chemistry, which must make his fame enduring, was that he showed how to avoid all this confusion. He described his system of chemistry, though not till he had tested it amongst his own students, under the title, " Sketch of a Course of Chemical Philosophy." * His method was to use the hypothesis of his countryman, Avogadro, as a means of arriving at the molecular weights of substances, v;hether elementary or compound, and to make the molecular weights thus obtained the basis for determining the atomic weights of the elements. The other atomic weight methods, specific heat, isomorphism, and chemical analogy were, as he showed, simply auxiliary methods. In i860, two years after the publication of these ideas, a conference of chemists met at Carlsruhe for the express purpose of considering the state of confusion into which chemistry had * II Niiovo Ci/uento, vol. 7, pp. 321-366, 1858. Translated in No. iS of the Aletnbic Club Reprints. •xxxiv Annual Report of the Council. 'fallen. It was attended by some one hundred and forty men of science, including Liebig, Wohler, Kekule, Kopp, Bunsen, Odling, Roscoe, Dumas, Wurtz, and Cannizzaro. The pessimism of the opening speakers gave Cannizzaro his ■opportunity. When Dumas declared that organic and inorganic chemistry were two distinct sciences, Cannizzaro was able to maintain the unity of the science, for he showed that both inor- ganic and organic chemistry ought to be submitted to Avogadro's hypothesis as a controlling principle. Kekule made the declara- tion that the physical molecule and the chemical were not always identical, and that purely chemical researches could be carried on independently of physical considerations. In reply, Canniz- zaro expressed his opinion that the physical and chemical molecules were absolutely identical, and he showed that the best way of establishing the molecular weight of a substance was by means of its vapour density. The hour and the man had come. Cannizzaro's two speeches constituted him the leader of the Conference. His suggestions, immensely aided by the dramatic circumstances in which they were made, were adopted by many of his hearers. His system of chemical formulae and atomic weights, the one still in use, rapidly supplanted the old systems. And not only was the change good in itself, by reason of the clearness which it introduced into chemistry, but it led to unexpected advantages. It led to the establishment of three great doctrines. In the first place, the doctrine of gaseous dissociation was a natural outcome of Cannizzaro's teaching. In the next place, with regard to the doctrine of Valency, Frankland declared that till the atomic weights were placed on " their present consiscent basis, the satisfactory development of the doctrine was impossible." Lastly, the periodic classification of the elements, in the judgment of Newlands and of Mendeleeff, could not have been worked out under any other system than that of Cannizzaro. One is glad tg think that the priceless service which Cannizzaro thus rendered lo chemistry was widely recognised. Annual Report of the Council. xxxv In this country the honours paid to him included the award of the Copley Medal by the Royal Society in 1891, and the invitation to deliver the " Faraday Lecture " to the Chemical Society of London. This invitation he accepted, and the lecture which he gave, under the modest title " Some Points on the Theoretic Teaching of Chemistry,'"^ is a lasting proof of what a great and winning teacher of chemical philosophy Italy produced in him. A. N. M. The Rev. Robert Harley, Hon. M.A. (Oxon.), F.R.S., &c., &c., who died at Westbourne Road, Forest Hill, London, on July 27th, 1910, had been a corresponding member of the Society since April 30th, 1850. Mr. Harley was born in Liverpool, January 23rd, 1828, and was the son of a Wesleyan minister. His interest in and capacity for mathematics developed so suddenly that, though he had passed his fourteenth year before mastering the multiplication table, he was at sixteen mathematical master in a school at Seacombe. After being a teacher for several years, Mr. Harley became a divinity student at Airedale College, Bradford (now the United College, Bradford), and in 1854, minister of the Congregational Church at Brighouse, a position he retained for fourteen years, during the last four of which he was also tutor in mathematics and logic at Airedale College. In 1868 he accepted a call to Bond Street Chapel, Leicester. During the four years he held this pastorate, he took an active part in the public work of the town, serving on the School Board, and being honorary curator of the town museum. From 1872 to 1881 he was vice- principal and chaplain of Mill Hill School. He was principal of Huddersfield College from 1882 to 1885, and in 1886 he removed to Oxford, where he was minister of George Street Congregational Church. He received the honorary degree of M.A. in 1886, and took the leading part in the foundation of the * Trans. Client. Soc, vol. 25, p. 941, 1872. xxxvi Annual Report of the Cowicil. Oxford Mathematical Society. Ill health compelled him to take a rest in 1890, and he visited Australia, taking temporary charge of a church in Sydney. After his return he became, in 1892, minister of Heath, near Halifax. In 1895 he retired from the ministry, and afterwards resided at Forest Hill, eagerly pursuing to the last his mathematical studies, and doing much honorary preaching, tem[jerance, and philanthropic work. It was as a mathematician that Mr. Harley attained dis- tinction, but science had never more than a secondary claim on his time. Of his mathematical work JSatiire says: — "The application of mathematics to logic, as developed by George Boole, captivated his intelligence, and he became the most notable of Boole's admirers and followers, as also his biographer. His greatest mathematical achievements were, however, in another field. The unsolved problem of the solution of quintic equations fascinated him. Having once granted the impossibility of the solution by radicals, he proceeded to exhibit with remark- able power and patience the place of certain sextic resolvents in connection with such equations. Simultaneously, the la'e Sir James Cockle was engaged on like work ; but Harley was the clearer writer on the difiticult subject. Their work, and in par- ticular Harley's, -was welcomed enthusiastically by Cayley, who himself took it up and continued it. All three probably were not aware at the time that certain continental writers had possessed some of their ideas beforehand ; but everyone must recognise that Harley's development of the ideas was masterly. Ii secured for him the Fellowship of the Royal Society in 1863." Mr. Harley was twice secretary, and three times vice- president, of the "A" Section of the British Association. His contributions to the literature of pure mathematics and symbolic logic were numerous. Of these, the following were contributed to this Society : — Papers : — *'On Impossible and certain other Surd Equations."' (1851,) Mem. (2) ix. 207. Animal Report of the Council. xxxvii ■"On the Method of Symmetric Products, and its Application to the Finite Algebraic Solution of Equations."' {1859.) J/«/«. (2) xv. 172. " On a certain Class of Linear Differential Equations." {1862.) Mcin. (3) li. 232. "On Bring's Reduction of the Equation of the Fifth Degree to a Trinomial Form." (1863 ) Proc. iii. 69. "On Recent Researches ou the Theory of Equations." (1863.) Proc. iii. 173. "On the Rev. T. P. Kirkman's Method of Resolving Algebraic Equations." (1868). Proc. viii. 4. ■" On the Interchange of two Differential Resolvents." (1891.) Mem. (4) V. 79. Minor Communications : — "On the Theory of the Transcendental Solution of Algebraic Equations.' (1862.) Proc. ii. 181, 199 and 237. "On Linear Differential Equations." (1862.) Proc. iii. 17. " Remarks on Mr. J. J. IMurphy's Paper * On the Quantification of the Predicate, and on the Interpretation of Boole's Logical Symbols.'" (1883.) Proc. xxiii. 36. "Obituary Notice of Sir James Cockle." (1895.) -^^^w- (4) ix. 215. F. N. By the death of Professor J. H. van't Hoff, which took ■place at StegHtz, near BerHn, on March ist, the world of science has lost one of its most brilliant investigators and careful and inspiring teachers. All who have had the privilege of working under the direction of Professor van't Hoff will bear testimony to the wonderful inspiration given by association with him, whilst his course of lectures on physical chemistry, given at the University of Berlin, will always be remembered, not only for the breadth of treatment, but also for the simple and clear manner in which they were delivered. Jacobus Henricus van't Hoff was born in Rotterdam, on August 30th, 1850. At the age of nineteen he entered the Polytechnicum at Delft, and after passing through the techno- logical course, proceeded to the University of Leyden, con- tinuing his studies later in Bonn, under Kekule, and in Paris, under Wurtz. After a very short career as docent, van't Hoff -was appointed professor of chemistry at the University of xxxviii Annual Report of the Council. Amsterdam, a post he held for eighteen years. In 1896 he- was elected a professor in the University of Berlin, delivering lectures on physical chemistry in the University, but carrying, out his research work with his pupils in a private laboratory in Charlottenburg. In a brief account it is impossible to do justice to the impetus given to research, especially in the domain of physical' chemistry, by the large number of investigations carried out by him. Three subjects, however, stand out most prominently. The earlier work of van't Hoff was chiefly in the field of organic chemistry, and in this connection his genius soon led to the formulation of a new idea with regard to structural organic chemistry. In 1874 a short pamphlet was published, which put forward the idea of three dimensional space formulge for organic compounds, and also expressed the now well known relation between optical activity and the presence of an asymmetric carbon atom. In the following year the book " La Chemie dans I'espace" appeared. This book contained a clear and full account of the " tetrahedral " carbon atom, and may be said to- have laid the foundations of the important science of stereo- chemistry. The work, however, which will be always pre-eminently associated with the name of van't Hoff appeared in 1886. In- this year van't Hoff put forward his views on the analogy between the laws relating to dilute solutions and the well known laws relating to gases. Using a number of experimental results obtained by Pfeffer, Traube, and others, in their investigations on osmotic pressure, he was able to show the applicability of the gas laws to dilute solution, and further that this close relation in the behaviour of dilute solutions and gases was thermodynamically necessary. It may be said that this develop- ment, along with the electrolytic dissociation theory of Arrhenius, . gave the first satisfactory theory of the general properties and , relations of dilute solutions. Annual Report of the Council. xxxix The third great development due lo van't Hoff was carried out in Berlin. A very careful and complete investigation into the conditions under which various simple and double salts crystallize, led to a clear statement of the general conditions governing this class of heterogeneous equilibria. With this work as a basis, he commenced the very laborious investigation into the conditions of formation of tlie Stassfurt salt deposits. A collected account of these researches, which were carried out in conjunction with the late Dr. Meyerhoffer and a number of pupils, has been published under tlie title of "Zur Bildung der ozeanischen Salzablagerungen." Even in such a brief account as is here presented, mention should be made of the publication, in 1884, of the celebrated "Etudes de Dynamique chimique," in which the author gives an account of his researches on the quantitative relations met with in the course of chemical reactions, and especially on the con- ditions of equilibrium. Many will undoubtedly remember his visit to Manchester on the occasion of the celebration of the centenary of Dalton's atomic theory. During his visit the honorary degree of Doctor of Science was conferred upon him by the University of Man- chester, thus adding one more to the long list of honorary degrees of which he has been the recipient. Many other honours, including the award of the Nobel Prize in 1901, were bestowed upon him by nearly all the well known scientific societies, but undoubtedly he will be remembered by chemists in general as a great pioneer and investigator, and by his pupils not only as a brilliant chemist, but also as a beloved and successful teacher. N. S. By the death of Sir William Huggins, O.M., K.C.B., F.R.S., on May 12th, 1910, this Society lost a distinguished honorary member, who for many years was one of the foremost xl Annual Report of the Council . pioneers in the new branch of science now known as Astro- Physics. Born on February 7th, 1824, he received his early education at the City of l^ondon School, and continued his training in mathematics, classics, and modern languages with the help of private masters. He also studied at home various branches of science, purchasing or constructing for himself the apparatus required for his experiments. Finally he decided to devote himself to astronomy, and in 1855 he erected the observatory attached to his residence at Upper Tulse Hill, in London, where his life's work was carried out. He began in the usual way l)y measuring positions of stars and he also made drawings of the planets. Work of this kind, however, did not satisfy him ; his mind was seeking for new methods of research. He describes with what pleasure he heard about this time of KirchhofTs discovery of the meaning of the Fraunhofer lines in the solar spectrum. This discovery came to him as an inspiration, opening up a new line of investigation, which he determined to extend, if possible, to all parts of the visible universe. The task of extending Kirchhoff's work to the spectra of the stars appeared very formidable, owing to the faintness of their light; but the stars have one great advantage over the sun, that the brightness of a star image increases with the hght collecting power of the telescope, and Huggins found it was possible, with a spectroscope attached to the eyepiece end of his eight-irch refractor, to make detailed comparisons of the dark lines in a number of stellar spectra with the spectrum lines of chemical elements. His standard of scientific work was very high, hinding the existing charts of spectra inconvenient for his purpose, he devoted the greater part of 1863 to mapping, with a train of six prisms, the spark spectra of twenty-six elements, using as a reference scale the spark spectrum lines of air. Being well Arniiial Report of the Conncil. xli equipped by his preliminary training to enter the new field of investigation, and employing, such sound methods, he was soon rewarded by a rich harvest of results, and for a number of years he was able to surprise the scientific world with important discoveries. One of the most striking of these was liis discovery of the simple bright line spectrum of nebuljc, which he observed with feehngs of awe, for the first time, on the evening of August the 29th, 1864. At that time there was a growing belief that all nebulae would ultimately be resolved into innumerable stats. He was able, however, to distinguish at once between nebulae, giving a bright line spectrum, and star clusters, giving a con- tinuous spectrum crossed by dark lines. When the difficulties of one line of investigation liad been overcome, Huggins was always ready to leave the smooth path for fresh difficulties. Almost from the beginning of his stellar work he had looked forward to so far perfecting his instruments and methods as to be able to detect displacements of the spectrum lines of the stars due to their motion towards or away from the earth. Finally, in 1868, he was able to announce that he had measured the velocity of Sirius. It is not surprising that many astronomers, who at that time had not ado])ted spectroscopic methods, did not regard his early work in this direction seriously. Huggins was quick to appreciate the advantages offered by photography. His first attempts to photograph spectra were indeed made before the dry plate was invented, and as early as 1876 he was employing an Iceland spar and quartz spectroscope attached to a reflecting telescope to extend his j)hotographs into the ultra-violet region. By his marriage in 1875 he secured an enthusiastic assistant in his scientific work. Lady Huggins collaborated with her husband in much of his later work, and the " Atlas of Repre- sentative Spectra," published in 1899, is a beautiful monument, both in a scientific and artistic sense, of their joint labour. xlii Annual Report of the Coiincil. To the end of his life Huggins remained remarkably acces- sible to new ideas, and when radium was discovered he under- took the task of photographing the spectrum of its spontaneous luminosity. He became President of the Royal Society, and indeed received almost every scientific honour that could be conferred upon him. In 1897 he was made a Knight Commander of the Bath, and on the foundation of the Order of Merit, at the beginning of King Edward's reign, he was one of the first to be enrolled. He was elected an Honorary Member of this Society irv 1 869. H.S. Treasurer^ s Accounts. Note. — -The Treasurer's Accounts of the Session 1910- 191 1, of which the following pages are sumniaries, have been endorsed as follows : April nth, 191 [. Audited and found correct. We have also seen, at this date, the certificates of the follouint;; Stocks lield in the name of the Society: — ;^i,225 Great Western Railway Company 5% Consolidated Preference Stock, Nos. 12,293, 12,294, ^f'4 9 64 19 24 3 1 3 o X:65S '7 ' NATURAL HISTOR To Balance, 1st April, 1910 .. To Dividends <.n ^^1,225 Great Western Railway Comjjany's block To Remission of Income Tax, 1910. . £.!(> JOULE MEMORIA To Balance, 1st April, 1910 To Dividends on ^258 Loan to Manchester Corporation 'lo Remission of Income Tax, 1910 Lm 1^ I To Balance 1st April, lyio To Dividends on ;i7,5oo Gas Light and Coke Company's Ordinary Slock To Remission of Income Tax, 1910 To Bank Interest WILDE ENDOWMEN' '79 -y J29 " ^sii Treasurer s At counts. HILOSOPHICAL SOCIETY. Hi(iy,from isl April, igio, to jisi Match, igii. xly f Charges on Property :— Chief Rent (Income Tax JeilucleU) Income Tax.. Insurance agaiiibt Fire yr House Expenditure : — Coals, Gas, Electric I.iglit. Water. .Vc Tea, Coffee, Ac, at Meetings Cleaning, Sweeping Chimneys, &c ("leaning and Repairing Pictures Replacements of mantles, crockery, dusters, etc y .Administrative Charges : — Housekeeper .. .-'^^ Postages, and Carriage of Parcels and of " Memoirs " Stationery, Cheques, Receipts, and Engrossing Printing Circulars, Reports, &c. ,• , " Extra attendance at Mertin-s, and during housekeeper's holidays Insurance against Liability I Gratuities to Mrs. Kelly .Miscellaneous E.\penses ;y Publishing : • I Printing " Memoirs and Proceedings" Illustrations for "Memoirs" (except Nat. Hist, papers) .. >y Library : — Books and Periodicals (except those charged to Natural H Periodicals formerly subscribed for by the Microscopical n Section . . Catalogue Cards and Cabinet . . iy Natural History Kund : — (Items shown in the Balance Sheet of this Fund below) . Jy joule Memorial Fund :- (Items shown in the Balance Sheet of this Fund below) Jy Wilde Endowment Fund (Income Tax refunded) t April, luii £ s. d. I 15 o 92 3 10 £i)i 18 10 FUND, 1910— 1911. By Assistant Secretary's Salary, April, 1910, to Maich, 191 1 By Maintenance of Society's Library: — Binding and Repairing Books .. By Repairs and Improvements to Society's Premises .. By Cleaning Carpets and Curtains By Upholstering Chairs By Transfers to Society s Funds By Cheque. Book By B.-*lance at District Bank, ist April, 1911 s. d. o o 113 o a 12 911 2170 80 9 o 026 149 12 4 ^5^1 10 11 clvi The Council. ' THE COUNCIL AND MEMBERS cv rnK MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. {Corrected to September St/u 'gi i-) Prof. F. E. WEISS, D.Sc, F.L.S. FRANCIS JONES, M.Sc, F.R.S.E., P'.C.S. ERNEST RUTHERFORD, D.Sc, F.R.S. ARTHUR SCHUSTER, Sc.D., Ph.D., F.R.S. FRANCIS NICHOLSON, F.Z.S. .Secictaiiee. R. L. TAYLOR, F.C.S., F.I.C. GEORGE HICKLING, D.Sc. W. HENR^- TODD. |£ibiaiian. C. L. BARNES, M.A. dDthfi' ^ttembcrs of the (Eouiuil. EDMUND KNECHT, Ph.D. WILLIAM BURTON, M.A. SYDNEY J. HICKSON, M.A., D.Sc, F.R.S. Sir THOMAS H. HOLLAND, K.C.LE., D.Sc, F.R.S. THO.MAS THORP, F.R.A..S. T. A. COW^VRD, F.Z.S. ^eaietaut Secretary nub liibrarian. A. V. HUNT, B.A. Or(Unary Mfinhfrs. xlvii ORDINARY MEMBERS. Dalt of KIrctivn. 191 1, April 4. Adanison, Arthur, A.K.C.S., Lecturer in Physics in the Municipal School of Technology, Manchester. Techtn'cal School, Sach'ille Street, Manchester. 1901, Dec. 10. Adamson, Harold. Oak/amfs Cottat^e, Coiiley, near Man- chester. 1902, Mar. iS. Allen, J. I'enwick. 147, IV'ithifiglon Road, Whaliey A'atige, Manchester. 1870, Dec. 13. Angell, John, F.C.S., F.I.C. (>, Heacomfield, Deihy Road, \Vithiiif;ton, Manchester. 1865, Nov. 14. Bailey, Charles, M.Sc, l'M..S. IJayvtesgarth, Cleeve Hill S. O. , Gloucestershire. 1888, Feb. 7. Bailey, Alderman Sir William H., M.I.Mech.E. Sale Nail, Sale, Cheshire. 1895, Jan. 8. Barnes, Charles L., M.A. 151, Plymouth Grove, Chorltou-on- Medlock, Manchester. 1903, Oct. 20. Barnes, Jonathan, F.G.S. South Clifi House, 301, Great Clowes Street, Higher Broughton, Manchester. 1910, Oct. iS. Beattie, Robert, D.Sc, Lecturer in Electrotechnics in the University of Manchester. The University, Manchester. 1895, Mar. 5. Behrens, Custav. Hollv Koyde, Withington, Manchester. 1898, Nov. 29. Behrens, Walter L. 22, Oxford Stteet, Manchester. 1868, Dec. 15. Bickham, .Spencer IL, F. L.S. Underdown, Ledbury. 1875, Nov. 16. Boyd, John. Barton House, \l, Didsbury Park, Didshury, Manchester. 1889, Oct. 15. Bradley, Nathaniel, F.C.S. Sunnyside, Whaliey Rangt., Manchester. 1861, April 2. Brogden, Henry, F.C.S., M.LMech.E. Hale Lodge, Altrincham, Cheshire. 1889, April 16. Broolis, .Samuel Herbert. Slade House, L.evenshulme, Manchester. 1910, Nov. I. Broome, James S., .Science Teacher in the Salford .Secondary School. 18, Seedley Park Road, Pendleton, Alancheslei . i860, Jan. 24. Brothers, Alfred. Handforlh, near Manchester. 18S6, Aj^ril 6. Brown, Alfred, .M. A., M.D. Sandycroft, Higher Brough- ton, Manchester. 1889, Jan. S. Brownell, Thomas William, F.l^.A.S. 64, Upper Brook Street, Manchester. xlviii Ordinary Members. J'ate of ElectttH. 1SS9, Oct. 15. Jiudeiibery, C. F., M.Sc, M.I.Mech.E. Bow Jon Lane, A/arpk, Cheskiie. 191 1, Jan. 10, Burt, Frank Playfair^ D.Sc.(Loncl.), Assistant Lecturer and Demonstrator in Chemistry in the Victoria University of Manchester. 5, Beaconsfield, Derby Road, Withhi^tou, A/aiichester. 1906, Feb. 27. Burton, Joseph, A. R.C.S. Dublin. I'ile IVorks, Cli/ion Junction, near Manchester. 1S94, Nov. 13. Burton, VVilham, M.A., F.CS. The Hollies, Cliftoit Junction, near Manchester. 1904, Oct. 18. Campion, Geortje Goring, I,.1).S. 264, Oxford Street, Manchester. 1907, Jan. 15. Carpenter, II. C. H., M.A., Ph.D., Professor of Metal- lurgy in the University t>f Manchester. 11, Oak Road^ II ilhington, xManchester. 1899, Feb. 7. Chapman, D. L., M.A., Fellow of Jesus College, Oxford. Jesus College, Oxford. 1901, Nov. 26. Chevalier, Reginald C, M.A., Matheaiatical Master at iiae Manchester Grammar School, i"]. Central Road, West Didsbuty, Manchester. 1907, Nov. 26. Clayton, Robert Henry, B.Sc, Chemist, i, Farkjield Road, Didsbury, Alanckester. 1895, April 30. Collett, Edward Pyeniont. 8, St. John Street, MumhesUr. 191 1, May 9.- Cook, Gilbert, M.Sc, A. M.Inst.C.E., Vulcan Research tellow in Engineering in the University of Manchester. 8, Clarendon Road, Garslon, Liverpool. 1903, Oct. 20. Core, William Hamilton, M.Sc. Groombrid^qe House, Withington, Manchesiei . 1910, Oct. 18. Cotton, Robert, M.Sc, Demonstrator in Engineering in the University of Manchester. IVesthoime, Devonshire Road, J 'en diet oil , A I a nchcstei '. 1906, Oct. 30. Coward. II. F., D.Sc, Assistant Lecturer in Chemistry in the University of Manchester. Municipal School of Technology, Sackvil.e .Street, Manchester. 1906, Nov. 27. Coward, Thomas Alfred, F.Z.S. Brentwood, Bowaon, Cheshire. ' 1908, Nov. 3. Cramp, William, M.Sc. Tech., M.LE.E., Con.-iulting Engineer. 20, Mount Street, Manchester. 1910, Oct. 4. Crewe, F. IL, Assistant Science Mastei' in the Municipal Secondary School, Whitworth Street. Glengarth, IVoodJord Road, Brui/ihall. Oniinary Members. xlix Date of Election. ■ , 191 1, April 4. Duiwiii, C G., U.A., Reader in Mathematical Pliysics in llie University of Manchester. The University, MatulicsUr. 1S95, April 9. Dawlvins, VV. lioyd, M.A., D.Sc, K.K.S., Honorary Professor of Geology in the \'ictoria University of Man- chester. Falloivfield House, Fallowfield, Mamhesier. 1S94, Mar. 6. Delepine, A. Sheridan, M.IJ., B.Sc. , i'lufessor of Patiiolo^y in the Victoria Univeisity of Mancliester. 7 he University, Manchester. 1S87, Fel.. 8. Dixon, Harold Baily, M.A., M.Sc, F.R.S., F.C.S., J'rofessor of Chemistry in the Victoria University of Manchester. Tlie Univeisity, Manihciter. 1906, Oct. 30. Edgar, E. C, D.Sc, Assistant Lecturer and IJcuionstralor in Chemistiy in the University of Manchester. 'J'he University, Mamhesier. 1910, Oct. 18. Evans, Evan [enkiu, B.Sc, .Vssistant Lecturer and Demonstrator in Physics in the University of Manchester. The University, Manchester. 1907, Nov. 26. Fiatteis, Abraham, F.K.M..S. Sydaal Cottage, Bramhall, C Jus hire. 1908, Jan. 28. Fox, Thomas William, ^LSc.Tech., Professor of Textiles in the School of Technology, Manchester University. 15, Clarendon Crescent, Eccles. 1909, Mar. 23. Gee, W. VV. Haldane, B.Sc, M.ScTech., A.M.LE.E., Professor of Pure and Applied Physics in the School of Technology, Manchester University. Oak Tea, il'hailey Avenue, .Sale. 1910, Nov. 29. Geiger, Hans, Ph.D., Research Student in the University of Manchester. 62, Nelson Street, Manchester. 1896, Nov. 17. Gortlon, Rev. Alexander, JNLA. Snini/ierville, ITctoria Tark, Manchester. 1907, Oct. 15. Gravely, F. H., M.Sc. Natural History Dept., Indian Museum, Calcutta. 1907, Oct. 29. Gwylher, Reginald Felix, M.A., Secretary to the Joint Matriculation Board. 21, Booth Avenue, ll'ithingion', Alancliesier. 1911, Oct. 3. Hasst, H. R., M.A., M.Sc, Lecturer in Mathematics in the University of Manchester. lOO, Tadyburn Lane. Ffillowfield, Manchester. 1902, April 29. Herbert, Arthur AL, B.A. Frankwyn, Hale, Cheskiie. 1902, Jan. 7. Hewitt, David B., ALD. Grove Mount, Daveiiham, Cheshire. I Ordinary Members. m Pate ef EUctioH. 1907, Oct. 15. Hickling, H. George A., D.Sc, Assistant Lecturer and Demonstrator in Geology in the University of Manchester. Glenside, ^larple Bridge, near Stockport 1895, Mar. 5. Hickson, Sydney J., M.A., D.Sc, F.R.S., Professor of Zoology in tlie ^'ictoria University of Manchester. The University, MaticJtestei . 1884, Jan. 8. llodgkinson, Alexander, M.B., B.Sc. 18,5/. /o//« Street, Atanchester. 1909, Jan. 12. Hoffert, Hermann Henry, D.Sc. (Lond.), A.R.S.M., His Majesty's Inspector of Schools. Lime Grove, Brook fands. Sale. 1909, Nov. 2. Holland, Sir Thomas H., K.C.I.E., D.Sc, F.R.S., Professor of Geology and Mineralogy in the University of Manchester, late Director of the Geological Survey of India. IVestivood, Alderley Edge, Cheshire. 1905, Nov. 14. Holt, Alfred, M.A., D.Sc, Research Fellow of the Uni- versity of Manchester. Crofton, Aigbttrth, Liverpool. 1898, Nov. 29. Hopkinson, Sir Alfred, K.C.,M. A., LL.D.,Vice-Chancellor of the Victoria University of Manchester. Lairfield. Victoria Park, Manchester. 1896, Nov. 3. Hopkinson, Edward, M.A., D.Sc, M.Inst.C.E. 'Ferns, Aiderley Ed^e, Cheshire. 1909, I'^el). 9. Howies, Frederick, M.Sc , Analytical and Researcii Chemist. 20, Moxley Road, Crumpsall, Manchester. 1889, Oct. 15. Iloyle, William Evans, M.A., D.Sc, F.R.S.E., Director of the Welsh National Museum, Cardiff. City Hall, Cardiff. 1907, Oct. 15. Iliibner, Julius, M.ScTech., F.I.C., Lecturer in the I'aculty of Technology in the University of Manchester. Ash Villa, Chcadle LLuhne, Cheshire. 1899, Oct. 17. Ingleby, Joseph, M.I.Mech.E. Suwvier LLill, Pendleton, Manchester. 1901, Nov. 26. Jackson, Frederick. 14, Cross Street, Manchester. 191 1, Oct. 17. Jackson, W. H. 77, Clarendon Road, Manchester. 1870, Nov. I. Johnson, William H., B.Sc. IVoodleigh, Altrinchain. 191 1, Oct. 3. Johnstone, Mary A., B.Sc.(Lond.), Headmistress of the Municipal Secondary School for Girls, Whitworth Street, Manchester. 11, Birchvale Drive, Romiley. 1878, Nov. 26. Jones, Francis, M.Sc, F.R.S.E., F.C.S. The Grammar School, Manchester . Oniinary Meinbets. \{ Datt 0/ EUctioH. 1886, Jan. 12. Kay, Thomas. Moor fie LI, Stockport , Cheshire. 1910, Oct. 18. Kershaw, Edith May, M.Sc, Demonstrator in Botany in the University of Manchester. Ash Meade, Upper Mill, Yorks. 1903, Feb. 3. Knecht, Kdnuind, Ph.D., I'rofessor of Chemistry in the School of Technolojjy, Manchester University. Beech Mount, Marple, Cheshire. 1893, Nov. 14. Lamb, Horace, M.A., LL.D., D.Sc, Sc.D., F. R.S., Pro- fessor of Mathematics in the Victoria University of Man- chester. 6, Willirahain Road, Falloivjield, Manchester. 1909, Nov. 2. Lang, William H., D.Sc, M.B., CM., F.K.S., Barker Professor of Cryptogamic Botany in the University of Manchester. 2, Heaton Road, Withington, Manchester. 1902, Jan. 7. Lange, Ernest F., M.LMech. K., F.C.S. Fairholni, 3, Willow Batik, P\illoivpie/d, Manchester. 191 1, Jan. 10. Lankshear, Frederick Russell, B.A. of N.Z. University, Demonstrator in Chemistry in the Victoria University of Manchester. 'J'he University, Manchester. 1910, Oct. 18. Lapworth, Arthur, D.Sc, Lecturer in Chemistry in the University of Manchester. 30, Antlierst Head, With- ington, Manchester, 1904, Mar. 15. Lea, Arnold W. VV., RLD. 246, Oxford Koad, Manchester. 1903, Nov. 17. Leigh, Charles VV. E., Lilirarian of the University. I'he University, Manchester. 1907, Oct. 29. Leigh, Harold Shawcross. Bient-wood, Worsky. 1908, Oct. 20. Liebert, Martin, Ph.D., Managing Director of Meister Lucius, and Briining, Ltd. , Manchester. Sivinton Plouse, IVil'nsloiv Rocui, Witliington, Manchester. 1902, Jan. 7. Longridge, Michael, M.A., M.Inst.C.E. Linkvretten, Ashley Road, Boivdoit, Cheshire. 1857, Jan. 27. Longridge, Robert Bewick, M.LMecli.E. Yew 'liee House, Tabley, I\nutsforU, Chesliite. 1866, Nov. 13. McDougall, Arthur, B.Sc. I.ynaliurst, 'I'iie P^ark, Buxton. 1910, Oct. 18. McDougall, Robert, B.Sc. City Corn Mills, German Street, Manchester. 1905, Oct. 31. McNicol, Mary, ^LSc. 182, Upper Chorlton A'oad, Manchester. 1904, Nov. I. Makower, Walter, B.A. , D.Sc. (Lond.), Lecturer in Physics in the University of Manchester. 214, Upper Brook Street, APanchestcr. Hi Ordinary Mciitbers. Date of Klfciitin. 1902, Mpr. 4. Mandlebcrg, (ioD Iman f linrlcs. I\eaiiyf)e, Victoria Park, ]\fanihfs ei . 1910, Oct. 18. Mangan, Joseph, M.A., Lecturer in Economic Zoology in tlii University of Mancliesler. 77ie University, illan- clu'ster. 1875, Jan. 26. Mann, J. Dixon, M.IX, F.R.C.l*. (Lond.), Professor df Medical Jiirispriuience in the Victoria University of Manchester. 16, .SV. /ohn Street, l\Taitchester. 1901, Dec. 10. -Massey, Herbert. A'j' I.ea, Jhirnasie, Didshiiry, Manchester. 1864, Nov. I. Mather, Sir William, r.C, M.Inst. C.E., M.I.Mech.K. 7ro>i IVor'.s, Sa!fo>,/. 1910, Nov. I. Matheson. Atherton Grevil'e Ewing, Mining Engineer. (iiiihtliall Cha'iibers, 38/40, Lloyd Street, Manchester. 1.873, '^'•"- '8- Melvill, James Cosmo, M.A., D.Sc, F.L.S. Meole-Brace Hall, Shrcivs/nny. 1S94, Fel). 6. Mon-l, Rolieit Liidwig, M.A., K. K.S.E., F.C.S. IVinttini;- lon JIall, Noi ihu'ich, Cheshire. 191 1, Ma\- 9. Moseley, Henry (jwyn JefFieys, B.A-, Lectuier in Physics in the University of Manchester. Dunivood House, II 'ithin^toti, Jfanchester. 191 1, Oct. 3. Mumford, A. A., M.I-i. Wilnislow Road, Withingtoii, Manchester. 1908, Jan. 28. Myers, William, Lecturer in Textiles in the School of Technology, >fanchester University. Acresfield, Gatley, Cheshire. 1873, Mar. 4. Nicholson, I'^rancis, !•"./. S. The Knoll, If indermere, JVestiiiprland. 1900, April 3. Nicolson, John T., D..Sc. , I'rofessor of I'Zngineering in the School of 'I'eclinology, Manchester University. Nant-)- Cilyn, Marple, Cheshire. 1884, April 15. Okell, Samuel, I'Mx.A.S. Overley, I.avi^ham Road, Hoicdon, Cheshire. 1907, Oct. 29. Oshorn, Theodore George Bentley, B.Sc, Lecturer in J''conomic Botany in the University of Manchester. Windlehurst , Anson Road, Victoria l^ark, ]\Tanchestet . 1892, Nov. 15. Perkin, W. IL, Sc.D., Ph.D., M.Sc, F.R.S., Professor of Chemistry in the Victoria I'niversity of Manchester. The University, J\fattches/er. Ordinary Members. liii Dntf of 1:1, <. I OH. 1901, ()<:!. 29. I'etavel, J. K., D.Sc, I'.R.S., Professor of ]'"nt;ineerini; in the Victoria University of Manchester. The Uni- versity^ J\/anc/iestet: 18S5, Nov. 17. I'hilHps, Henry Harcourt, I''.C.S. l.ynivood, 'J'ur/on, nr. Bolton, Lanes. 1903, Der. ;5. I'lentice, Bertram, I'h.D., D.Sc, Principal of the Koval • ■ Technical Institute, Salford. hca Mount, J/aw//??.'?;- ■ ■'* Road, .Sivinton. ■ 1-977, Oct. 17. Pring, J. N., D.Sc, l^ectarer and Demonstrator in Electro- chemistry in the University ci Manchester. The Uni- vetsity, Manchester. 1 901, Dec. 10. Ramsden, Herbert, M.D. (I>ond.), M. B., ("li. H. ( Vict. ). SunnysiJe, Dobcross, near Oldham, J.ancs. 1888, Feb. 2t. Kee, Alfred, Ph.D., F.C.S. 15, Mauhieth Road, With- ington, Maiuhesier. 1908, Nov. 3. Reekie, J. A., Manager of the Hayfield I'rintwcrks. Buck ton Grange, Stalybridgc. 1869, Nov. 16. Reynolds, Osborne, M.A., LL.D., F.R.S., M.Inst. C. K. .SV. Decuman s, IVatchet, Somerset. 1910, Oct. 4. Rhead, E. L. , M.Sc.Tech., F.I.C-, Lecturer on Metallurgy at the Municipal School of Technology, Manchester. Stonycroft, Polygon Avenue, Levenshulme, Manchester. 1880, Mar. 23. Roberts, D. Lloyd, ]\LD., F.R.S.E., F.R.C.P. (Lond.) Ravensrvood, Brougliton Park, Matichester. 191 1, Jan. 10. Robinson, Robert, D.Sc. (Vict.), Teacher of Cheniislry in the Victoria University of Manchester. Field House, Chesterfield. - igro, Oct. iS. Rossi, Roberto,- M.Sc, Student. Dalton Ifull. J'ictoria Bark, Mancheiter. 1897, Oct. 19.. Roihwell, Williara Thomas. J death Breivery, N-'ic/on Heath , near Manchester. 1907, Oct. 15. Rutherford, Ernest, M.A., F.R.S., Langworthy Professor of Physics in the University of Mancliester. 17, Jii/ws- low Road, IVithington, Manchester. 1911, Oct. 17. Sandiford, Peter, M.Sc, Ph.D. Lecturer and Deinnn- strator in Education in the University of Manchester. The University, Manchester. J909, fan. 26. Schmit7, Hermann Emil, M.A., P.Sc, I'hysics l\!asier .nt the Manchester Grammar .School. 15, Brighton' Ci ore, Rushoiii/e, Manchester. liv Ordinary Members. V»lt of Election. 1873, Nov. 18. Schusler, Arthur, Sc.D., I'li.U., F.R.S., F.K. A. S., Honorary Professor of Physics in the Victoria University of Man- chester. Ketit House, Victoria Park, Manchester. 1898, Jan. 25. Schwabe, Louis. HaH Hill, Eicles OUi Road, Pendleton, Manchester. 1908, Nov. 17. Schwartz, Alfred, A.K.C., M.Sc.Tech., M.I.E.E., AssocM.Inst.C.E., Professor of Electrical Engineering in the School of Technology, Manchester University. Monrne /^od ?'yii RECENT ADDITIONS TO THE LIBRARY Presented. Batavia.- Bataviaasch Genootschap van Kunsten en Weten- schappen. Ethnographica in het Museum van het Batav. Genoot- schap. ris. i. — xii. Door J. W. Teillers. Weltevreden, etc., 1910. {kecd. sILx.fio.) . Rapporten van de Commissie in Nederlandsch- Indie voor Oudheidkundig Onderzoek op Java en Madoera 1908. Batavia etc., 1910. [Reed. iiJAi.jio.) Budapest. — Magyar Tudomanyok Akademia. Sermones Doniinicales... bevezetessel es szotanal ellalta Szilddy Aron. Kot. i., ii. xx. +661, and 764 pp. Budapest, 19 10. (/iecd. jlf'.v.j/o.) Copenhagen. — Kgl. Danske Videnskabernes Selskab. Ole Romers Adversaria. JNIed understottelse af Carlsbergfondet udgivne . . . ved T. EibeogK. Meyer. [4] 4 271 pp. Kobenhavn, 1910. {I\eid. jj/.j/'i.) Durning-Lawrence (Sir E.). Bacon is Shakespeare. By Sir E. Durning- Lawrence. London, 1910. (Kecd. ^lix./io.) Kiel.— K. Christian-Albrechts-Universitat. [136 Dissertations.] 1908- 1910. [Rccd. sj'x.fio.) Liverpool. — Geological Society. Retrospect of 50 years" existence and work (of the Liverpool Geological Society). By W. Hewitt. 117 pp., 6 pis. Liverpool, 1910. [Reed, jofv.jro.) London. — British Museum (Natural History). Catalogue of British Ilymenoptera of the Family ChalcididK. By C. Morley. 74 pp- London, 1910. (Rad. 14IXJ.I10.) .— Guide to the British Vertebrates exiiibited in the Dept. of Zoology. 122 pp., plan, and 26 figs, London, 1910. (Rcrd. i^/x/.f/o.) . Guide to the Crustacea, Arachnida, Onychophora, and Myrio- poda exhiliited in the Dept. of Zoology. 133 pp., 90 figs. London, 1910. (Rc:d. /4lxi.//o.) . — Memorials of Charles Darwin. A Collection of Manuscripts, etc., to commemorate the Centenary of his Birth, etc. 2nd ed. SOPP-) 2 pis. London, 1910. {Reed, i^jxi.jio.) . — Meteorological Office. The Trade Winds of the Atlantic Ocean. By I\L W. C. Hepworth, J. S. Dines, and E. Gold. 45 pp., 18 pis. London, 1 910. (Reed. lojix-lio.) Vol. 55 -. Part II. MEMOIRS AND PROCEEDINGS OF THE MANCHESTER LITERARY & PHILOSOPHICAL SOCIETY, 19 10-19 1 1. CONTENTS. Memoirs : V. The Development of the Atomic Theory : (4) Dalton's Physical Atomic Theory. By Andrew Norman Meldrum, D.Sc. - pp. 1—22. (Issued separately, March yth, igil). VI. The Development of the Atomic Theory : (5) Dalton's Chemical Theory. By Andrew Norman Meldrum, D. Sc. - - - - pp. i — 18. {Issued separately, March yth, igil). VII. The Behaviour of Bodies floating in a Free or a Forced Vortex. By Prof. A, H. Gibson, D.Sc. JVith Text-Jig. - - - - pp. i— 19. (Issued separately, March yth, igil). VIII. Studies in the Morphogenesis of certain Pelecypoda : (i) A Pre- liminary Note on Variation in Unto pictorum. Unto tumidtis and Anodonta cygnea. By Margaret C. March, B.Sc. Plate and j Text-figs. pp. I — 18. (Issued separately, March /4th, igu). IX. On an Abnormal Spike of Ophioglossum vulgatum. By H. S. Holden, B.Sc, F.L.S. With 6 Text -figs. pp. I— 13. {Issued separately, March 2ist, igil). X. The Boric Acids. By Alfred Holt, M.A., D.Sc. IViih 2 Text-figs. pp. 1—9. {Issued separately, April loth, igii). [Continued on p. 4. MANCHESTER: 36, GEORGE STREET. Iprlcc Seven SblUfngs anD Sljpence. RECENT ADDITIONS TO THE LIBRARY. Presented. Brothers (A.) Photography : Its History, Processes, Apparatus and Materials. By A. Brothers. 2nd ed., revised. London, 1899. (Reed, s^liv.jii.) Cambridge, Mass. — Harvard University Library. A Herbert BibHo- graphy. By G. H. Palmer. (Bibliographical Contributions. No. 59.) Cambridge, Mass., 191 1. [Reed, sjliv-jii.) Canada. — Geological Survey. Report on a part of the N.W. Territories drained by the Winisk and Attawapiskat. By W. Mclnnes. Ottawa, 1910. [Reed. d/tz?./i/.) Cincinnati.- Lloyd Library. Synopsis of the sections Microporus, Tabacinus and Funales of the Genus Polystietus. By C. G. Lloyd. Cincinnati, 1910. (Reed, iijiv.lii.) . — Synopsis of the Genus Hexagona. By C. G. Lloyd. Cincin- nati, 1910. (Reed, ii/zv.///.) Gbrlitz.— Oberlausitzische Gesellschaft der Wissenschaften. Codex diplomaticus Lusatia' superioris iii....Herausg. von Prof. Dr. R. Jecht. Hft. 6. GorHtz, iqio. (Reed. /S/t.///.) Janet (Ch.) Sur la Morphologic de I'lnsecte. Par Ch. Janet. Limoges, 1909. (Reed. ly/ni./i/.) Sur 1 Ontogenese de I'lnsecte. Par Ch. Janet. Limoges, 1909. (Reed. I"/ 1 Hi. 1 1 1.) Note sur la Phylogenese de I'lnsecte. Par. Ch. Janet. Rennes, 1909. (Reed, jyliii.lif.) London. — Metropolitan Water Board. Sixth Report on Research work on. ..Typhoid bacilli. By A. C. Houston. [London], (1910). (Reed. lyjii.JTi.) Manchester.— Manchester Museum. Catalogue of Egyptian Antiquities of the Xn. and XVIIL Dynasties in the... Museum. By A. S. Griffith. Manchester, 19 10. (Reed. 3Slnz'./i/.) . Outline Classification of the Animal Kingdom. By S. J. Hickson. 4th ed. Manchester, 191 1. (Reed. ^Sliu./ii.) Miinchen. — Kbniglich Bayerische Akademie der Wissenschaften. Carl von Voit. Von O. Frank. Miinchen, 1910. (Reed. 7///.///.) Vol. 55 : Part III. MEMOIRS AND PROCEEDINGS OF THE MANCHESTER LITERARY & PHILOSOPHICAL SOCIETY, 1 9 10-19 II. CONTENTS. Memoirs : XXI. Dioptriemeters. By Prof. W. W. Haldane Gee and Arthur Adamson. With 8 Text-figs. ------- pp. i — 16^ {^Issued separately, June 1st, iQil). XXII. The Development of the Atomic Theory : {7) The Rival Claims of William Higgins and John Dalton. By A. N. Meldrum - pp. i— 11. (^Issued separately , Jutie I2ih, tgii). XXIII. On a Specimen of Osleocella septentrionalis (Gray). By Sydney J. Hickson, F. R.S, With 3 Text figs. - - - - - -pp. 1—15. (Issued separately, June l6th, igii). XXIV. An Account of some Remarkable Steel Crystals, along with some Notes on the Crystalline Structure of Steel. By Ernest F. Lange, M.I.Mech.E., etc. 2 Pis. pp. i— 15. (Issued separately, A ugust 2lst, igii). Proceedings - - - - - - - - - -pp- xxiii. — xxviii* Annual Report of the Council, with Obituary Notices of Prof. S. Cannizzaro, Rev. Robert Harley, F.R.S., Prof J. H. van't Hoff, and Sir William Huggins, O.M., K.C.B., F. R.S. - - - - - - - pp. xxix — xlii. Treasurer's Accounts --------- pp. xliii. — xlv. List of the Council and Members of the Society - - - pp, xlvi. — Ixi. List of the Awards of the Dalton Medal - - - - p. Ixi. List of the Wilde Lectures ------- pp. ixii — Ixiii. List of the Presidents of the Society - - - - - pp, Ixiv, — Ixv Title Page and Index --------pp. i. — xii. MANCHESTER: 36, GEORGE STREET. Ipricc ZbKZC SbilKngs. October 31st ^ igii. RECENT ADDITIONS TO THE LIBRARY. Presented. Bombay. — Government Observatory. Magnetic Observations made at... Bombay, 1846 — 1905, and their discussion. Pts. i and 2. By N. A. F. Moos. Bombay, 19 10. {Reed. 26lvii.\ii.) Canada. — Geological Survey. Geology of an Area adjoining the East side of Lake Timiskaming. By M. E. Wilson, Ottawa, 1910. {Reed. 2b\vii.\ii.) Copenhagen. — Kgl. Nordiske Oldskriftselskab. Nordiske Fortids- minder udg. afdet... Oldskriftselskab. Bd. ii. Hfte i. Kj0benhavn, 191 1. {Reed. 8lviii.\ii.) Gouy (M.) Sur la Structure et les Proprietes des Rayons Magneto- cathodiques dans un Champ uniforme. By M. Gouy. Paris, 191 1. (Reed. J2lvi.lii.) Greenwch. —Royal Observatory. Investigation of the Motion of Halley's Comet from 1759 — 1910. By P. H. Covjrell...and A. C. D. Crom- melin... Edinburgh, 1910. (Reed, jilviii.lii.) Madison. — Wisconsin History Commission. The Chattanooga Cam- paign. By M. H. Fitch, n. pi., 191 1. {Reed, /j/mii.jii.) . Wisconsin Women in the War between the States. By E. A. Hum. n. pi., 1911. {Reed, ijlvin.jii.) Marsden (V. E,) Finland: The Question of Autonomy and Fundamental Laws. By N. D. Sergeevsky. London, 191 1. {Reed, ijjvttt./ii.) Miinchen. — K. B. Akademie Wissenschaften. Verlags-Katalog. Miinchen, 191 1, (Reed, islvi.fri.) . Die Kunstpflege der Wittelsbacher. Von S. v. Riezler. Miinchen, 1 9 1 1 . (Reed, islvt. ///. ) . Wissenschaftliche Richtungen u. philosophische Probleme im xiii. Jahrhundert. Miinchen, 1910. (Reed. i2lvi.lii.) Oxford. — University Observatory. Astrographic Catalogue, 1900*0. Oxford section, Dec. + 24° to + 32°. Vol. 7. Prepared under the direction of H. H. Turner. Edinburgh, 191 1. (Reed, sdlvii.lii.) Reuss (E.) Electrolytic Bleaching and the Manufacture of Hypochlorites by Electricity. By E. Reuss. Leeds, 191 1. (Reed, isjvi.lii.) Schuster (A.) The Progress of Physics during... 1875—1908. By A. Schuster. Cambridge, 191 1. (Reed. 4lz>m.//i.) RECENT ADDITIONS TO THE UBRARY. —ConUnued. Washington. — Bureau of American Ethnology. Handbook of American Indian Languages. Pt. i. By F. Boas. Washington, 191 1. {Reed. I2\vi.lii.) . — Preliminary Report on a Visit to the Navaho National Monument, Arizona. By J. W. Fewkes. Washington, rgii. {Reed. 26lvii.l1 1.) . Indian Tribes of the Lower Mississippi Valley. By J. R. Swanton. Washington, 191 1. (Reed, sd/vu./ii,) . Antiquities of the Mesa Verde National Park Cliff Palace. By J. W. Fewkes. Washington, 191 1. {Reed, i^jviii.jii.) . — Indian Languages of Mexico and Central America. By C. Thomas and J. R. Swanton. Washington, 1911. {Reed, /j I vizi, j 11.) New Exchanges. Haarlem. — Teyler's Godgeleerd Genootschap. Verhandelingen, London. — Society of Chemical Industry. Journal. Manchester. — Micrologist (The). Princeton, N.J. — University Observatory. Contributions. And the usual Exchanges a?id Periodical? RECENT ADDITIONS TO THE UBRAR\ .—Coiihnued. Prag. — Kaiserlich-Konigliche Sternwarte. Die Reise der deutschen Expedition zur Beobachtung des Venusdurchganges am 9-Dezember 1874 nach der Kergueleninsel u. ihr dortiger Aufenthalt. Von Prof. Dr. L. Weinek. Prag, 191 1. (/iecd. iSli-jii.) Prag.— Koniglich Bohmische Gesellschaft der Wissenschaften. Nejstarsi Breviar Chrvatsko-Hlaholsky... Josef Vajs. V. Praze, 1910. (Reed. 25\iv.jii.) . — Untersuchungen iil)er den Lichtwechsel alterer veranderlichen Sterne. Nach den Beobachtungen von Prof. Dr. Vojtech Safarik, von L. Pracka. Prag, 1910. (Heed, ^jjiv.!//.) Stockholm. — Kungliga Svenska Vetenskaps-Akademi. Les Prix Nobel , 1908. Stockholm, 1909. (A'ecd. ^S/it.///.) Tait (W. A.). Life and Scientific Work of Peter Guthrie Tait. By C. G. Knott. Cambridge, 191 1. (Reed. 2^liv.lii.) Upsala. —Kungliga Vetenskaps-Societeten. Tvahundraarsminne, 1910. Upsala, 19 10. (Reed. 24lii.j/i.) Utrecht. — Koninklijk Nederlandsch Meteorologisch Instituut. Rapport sur I'Expedition Polaire Neerlandaise... 1882/83. Par M. Snellen... at H. Ekama. Utrecht, 1910. (Reed, ijjii.lii. Washington. — Bureau of American Ethnology. Handbook of American Indians North of Mexico. Part 2. Ed. by F. W. Hodge. (Bulletin 30). Washington, 1910. (Reed. 17/111. //i.) Zempleni (Arpad). Istar und Gilgamos...Ubertrag. v. J. Lechner von der Lech. Budapest, 191 1. (Reed. iS/z'./ii.) New Exchanges. Bamberg. —Remeis-Sternwarte. Veroffentlichungen. Leiden.— Rijks Herbarium. Mededeelingen. And the usual Exchanges and Periodicals. CONTENTS— Cf?«//«?W. Memoirs : XI. Studies in the Morphogenesis of certain Pelecypoda : (2) The Ancestry of Trigonia gibbosa. By Margaret Colley March, B.Sc. Plate and J Text-figs, ---..-... pp. i — 12. (Issued separately., April 20th, igti). XII. Some Physical Properties of Rubber. By Prof. Alfred Schwartz and Philip Kemp, M.Sc.Tech. With 11 Text figs. ■ pp. i — 22. UsiUid separately , May 2nd, igil). XIII. The Manner of Motion of Water Flowing in a Curved Path. By Prof. A. H. Gibson, D.Sc. pp. 1—5. (Issued separately. May 4t/i, igil). XIV. On the Periodic Times of Saturn's Rings. By Henry Wilde, D.Sc, D.C.L., F.R.S. pp. 1—3. (Issued separately. May Stli, /(?//). XV. Studies in the Morphogenesis of certain Pelecypoda : (3) The Ornament of Trigonia clavelLita and some of its Derivatives. By Margaret Colley March, B.Sc. With /j Text figs. pp. i— 13. (Issued separately. May jotit, igil). XVI. A Plesiosaurian Pectoral Girdle from the Lower Lias. By D. M. S. Watson, M.Sc W'itk 3 Icxtfigs. - pp. 1—7 (Issued separately. May tqth, igii). XVII. The Upper Liassic Reptilia. Part 3. Microcleidus macropterns (Seeley)and the Limbs of Miaodcidiis hoinalos/